Honestly the biggest hurdle is all the bookkeeping. Not just for characters & covenant -- although that's a lot -- but for antagonists.
The skill packages in Grogs and rules for magical creatures in RoP:Magic are good, but what would really help is if they were automated. And character/covenant tracking software would help too. Probably outside the scope of what Atlas would get up to, but maybe with an open license it might be feasible for someone else.
One of the ideas that we need to get across to new players to avoid disappointment is that you don't want to do advancement and lab work at the table, or at least not at the same time that you're rolling dice and talking with NPC's.
Perhaps the automated software would make the game more appealing for some, but I am skeptical of someone being able to create a program that both makes things considerably easier and doesn't screw stuff up.
My personal preference is to do everything on a spreadsheet where I can go back and see the values that went into each total and where I can still experience the story that numbers are telling. The strength of Ars Magica is how descriptive the mechanics are. The conversation that the players have about the magic is very close the conversation that the characters have about the magic. Having the mechanics done by a program is like getting the Cliff's notes for a book that you'd have preferred to have read yourself. That's my preference and not necessarily what everyone wants, but I am a bit leery of pushing new players into skipping a thing that's really rewarding.
On the other hand, I am completely in favor of automating upkeep of NPC's. To my mind they exist only to provide challenges and detail to the stories of the PC's so it wouldn't have to be "right" it would only have to be believable. A tool to quickly update any NPC's would be nice, but then you'd have to stat them out in the first place that would involve having those numbers in the software. It isn't a sure thing that you could craft a software that made this less work rather than more work.
You're making great accurate points written in a very clear manner. Thanks for that. I enjoyed reading your post. 
I truly think the same about the first part of the text. It would truly take something magical out of the game. Although, I can see some people could see it as a good thing. Not all people love to get nerdety nerdy about magic.
At the same time, I do agree with you to a certain degree with your point about the second problem, I also disagree a bit. Just a bit. I happen to be one of those players and Game moderators who love to dibble dabble with NPC creations and who enjoy the bookkeeping about the changes in NPCs. Yes, I admit I am a bit weird. 
Ideas I have so far:
Solo adventures for Ars - the one in the Runequest starter box encourages you into the game setting and some rules, and I have fond memories of the one in the little red book for D&D. (In fact, given people's laments about wanting more Ars or not being able to join a game, I've had thoughts of creating a fanzine full of ideas for satisfying that urge only Ars Magica can fill and calling it Ludi Solitarii )
A jumpstart saga - over the years many people have mentioned the lack of a published saga for Ars Magica (including me, and I've asked about what would make a good published saga). A good one for new characters, giving a sequence of adventures and how things could progress, could make a really good addition and help reduce the learning curve for new GMs. (I could even bundle in advice on running sagas and call it Liber Tirocinii as the latin term "tiroconium" can be used to refer to a soldier's first campaign or a craftsman's apprenticeship)
A set of adventures designed for troupe play - as troupe play is one of Ars Magica's great strengths, a set of adventures using different bits of the setting so everyone can have their own little sandbox could be great. I'd envision having a set of booklets, each to be read by the person who would SG that area (or all to be read by one person if you have a single SG). One booklet with covenant grogs in, and an adventure where the grogs have to try and fix problems without bothering the magi. One booklet detailing a nearby monastery and a healing well, and an adventure involving the divine. One booklet on a nearby hazardous area, and a vis hunt adventure and a couple of monsters statted. One booklet on a covenant in the same tribunal, and an adventure where the magi go to visit. This could make a great set and be useful both in encouraging troupe play and as a set of adventures and setting material for new SGs to use.
Oh, wow! Yeash, I truly welcome the Ludi Solitarii with open arms and from the bottom of my heart <3
And I also love your ideas on Liber Tirocinii.
I also dig your ideas on promoting troupe play.
Well, since several months, I am working on a new version of Solo Play rules for Ars magica. Time to finish it up and have it ready to share.
For those who would like to look how the last version looks like:
An example of Solo-play
And my initial pitch for DMless saga (including links to second to latest version of the rules)
Perhaps the automated software would make the game more appealing for some, but I am skeptical of someone being able to create a program that both makes things considerably easier and doesn't screw stuff up.
There certainly are challenges with that, but I think a (high-quality) software for character and covenant management would go a long way to make ArM more approachable and reduce the required time investments between sessions. It is a lot of work, though, and would have to be a team effort, I think.
Yes, sounds exactly like something that needs a team to be made well.
Even though I'm not a person who likes to use apps much, I see the demand for them. A well-made app would most certainly help players to get in the game.
The things is covenant management is entirely optional. Sure, there are detailed rules to balance a covenant budget, but it is pretty easy for a troupe to agree to handwave the detailed accounting and just go for broad strokes:
Players like different types of fun (theory of the eight type of fun for those interested, there are much more detailed articles than this wikipedia for those who want to understand what is happening around their table and why some games work and other don't): challenges (resolving them, being confronted to them) is one of them. Detailed management of covenant budget is a mini-game within the larger RpG ArsMagica, but it entirely is optional. I would not like to see resources allocated to building a covenant management program diverted from more essential part of the game.
Same with turbula management. It is another mini-game. Usually, the need/want to manage precisely grog development outside of RpG comes from the need to optimise certain aspects of the game. Again entirely optional.
I believe, one approach not to scare away new players is to clearly state what is optional and what is the bare minimum: generic description of what means Spring/Summer/Autumn/Winter covenants, with random tables to generate library (rolling a dice for quality and another for Level for example). Laboratory simplified to just "General quality" with a cost of virtus to progress, no size, no specialisation, no safety.
A few shield grogs to soak up some damage and avoid initially any mass combat (unless you have ways to simplify it). Don't bother with any other type of grogs until you want to run adventures with them - usually, new players want play with the big shiny toys, aka mages or possibly companions.
Etc...
The rules for more detailed creation/management exist once somebody wants to jump into it and take responsability for it and can be gradually introduced as players want to dig into certain aspects of the game.
When I started ArsMagica, I was a completionist and a min-maxer, so of course, I wanted to do everything. But not everybody around the table wanted to the same things, so instead of burdening the SG with all the options, we trimmed it down.
that sounds even less plausible than Hermetic magic in real life
That sounds about right 
But You can always try 
Will there be newbies?
The impression I got was that Anno Magical was intended as a a sort of revised edition for veteran players.
That being said, I had an idea for an Ars Magica product - It would have, basically been similar to Semita Errabunda, but bundled with a couple of story hooks a piece for the mage and companion characters and maybe a playthrough or two....
As I understood, it is meant for both: the new players and the veterans.
Yes, maybe. Although other games and their communities have managed some pretty impressive feats in this regard. Two examples that come to mind are Lancer and Pathfinder 2. Lancer has Comp/Con, an excellent fan made app that makes it a lot more approachable by offering character management and resource tracking for combat. Pathfinder 2 has Pathbuilder, which is also excellent and, I think, has done a lot to help new players handle the games numerous character options.
Both games also have very good (community maintained) support for Foundry VTT.
Quite a lot is possible with modern technology and determination. But it takes someone to take up the Chalange and a community to rally behind them.
To be completely honest, although I appreciate the suggestions for new adventures/sagas catering to beginners, I will say what I would have killed for two years ago, when I was starting as a storyteller in this game: A clear and comprehensive manual on how to run and design your Ars Magica saga. There were a myriad of questions I didn't know the answer for, and if it wasn't for the amazingly dedicated community this game has (and my stubborness and love for Ars Magica), I would have stopped entirely.
Simply put: running this game as a beginner storyteller is a complete nightmare. I would clarify and put simple and reproductible methods and frameworks so that anyone can convince their players to try this game out and continue playing it without losing all your hair due to stress. I would answer questions like:
Yes, this list is long, but please don't tell me the answer to these questions is 'Just take a look at what's published and wing it' because I don't think it's a serious answer. If I am a newbie storyteller, I think it's reasonable to want to know how I can make this game mine, not take what others wrote and just run it without thinking. As fun as running Calebais might be, it will never feel as authentic as creating something from the ground up with my troupe... and it's really, really, really hard to do it with what's published. I sincerely think that's one of the big failings of the Ars Magica line.
As far as I know, Justin Alexander is RPG Designer at Atlas. His recent book has been a success, and while I've not read the totality of it, I believe that many of the tools, lessons and frameworks presented in it would benefit Ars Magica greatly. It would benefit storytellers new and old, and in turn would make the experience of running this game a whole lot more pleasant, thus creating community. People would make more audiovisual content for this game (which is lacking due to the steep learning curve of many concepts) and the incoming open license would only help further.
Just my two cents on this topic. Sorry if I come off as angry, this is just a topic I think about weekly, and this thread hits pretty close to home.
I had more or less the same questions when I started as the Storyteller, and I'd played in a saga before. These are very legitimate and the varying difficulty in answering these questions are part of the steep learning curve of ArM. I'd say that picking the Tribunal might be the easiest one to answer: pick the location that is most inspiring to the storyteller. I picked the Rhine Gorge saga because I know the locations personally, (I realise that this is less helpful to a native of Chile or Japan) project redcap has a good guide, but having some kind of chart in the main book to decide: do you want a high/average/low Vis Tribunal, do you want an organised Order, neutral or a free for all., would be nice.
This would already split the tribunals into a 3x3 grid that many RPG players would be familiar with.
I would say that "How do I manage all the factions that will act in my saga?" is a more general than ArM specific question.
"How do I design a Hook or plant a Story Seed in my Saga?" could be answered with a half page sized box with both theoretical discussion and 2-3 worked examples. (local noble/clergyman that you have contact with sends you a message asking for help with X, your grogs heard rumour X while drinking at the local alewife's...)
Yes, I realize many of these questions are more of a general storyteller question rather than an AM question. But I was thinking in terms of 'I literally just bought this game yesterday and I've never ran a ttrpg session before, do I have everything I need here?' and the answer in the case of 5th Ed Core book is 'lol, of course not'.
I've read quite a lot of TTRPG books, and the absolute best ones are the ones that teach me not only how to run a game, but this game.
Honestly, I can't imagine anyone starting with ArM as their very first TTRPG. It's pretty niche and the overall complexity put it too far in my view from beginner hands. To use an analogy, people start drinking cider/beer then wine and then hard liquor. Jumping straight to a peaty smoky Whisky with no prior experience is a recipe for choking on a mouthful.
I don't necessarily disagree, but how's the n00b to know this?
Yep, that's what I was going to answer. I see a cool game, I like medieval history, I like wizards! Nice! How do I run it tho?
I don't think it's reasonable to put 'please run some D&D campaigns before you start with this game' at the start of your book. Complexity is not an excuse for lack of frameworks and foundations to make new people welcome.