Is there some errata for the Magic Memory virtue from the ArM5 main book?
As read it seems rather weak, in that it does not acknowledge your exposure to your parens' lab notes and lab activities.
By that, I am assuming that the majority of apprentices will at some point in their apprenticeship assist their parens in the laboratory, and/or be required to copy lab notes and other documents involving lab creations.
So I was expecting that a just-gauntletted magus with Magical Memory would go out into the world with the equivalent of a certain amount of lab notes from their parens.
Say the equivalent of 60 levels worth of spell creation/enchantment lab notes, that can be decided by the troupe (and if you are really generous, decided after character creation). Perhaps Skiiled Parens and Weak Parens might change this, say +/- 30 levels.
It does seem rather weak, but it might be of great use to a very poor itinerant magus, who has a tiny lab in a cart pulled by a donkey, and no real space to keep texts, or much of anything else, really. Could apply to Magi in a military campaign as well. In a Saga where Apprentices are routinely tasked with creating devices from Lab Texts, or where Magi are expected to serve their Covenant by doing so on the regular, this virtue might not be so bad.
Perhaps, as you put forward, a troupe decision to grant 60 levels of Lab Texts at character creation -I'd suggest for some charged devices- is a good idea, although I would not link these levels to Skilled Parens/Weak Parens in any way.
In the link to the Errata I saw nothing to suggest that anything about it has been changed.
If a character with the minor virtue Magical Memory uses a Casting Tablet, do they then remember enough to effectively recast the Casting Tablet even if they no longer posess the Casting Tablet?
Unless there is some errata, no, its just for remembering your own previous works in lab... using a Casting Tablet it not designing something into the lab. So, lab texts only.
To me, this minor virtue is just too weak... I'd say that its much better to just increase your Art of Memory ability.
My suggestion would be to combine magical memory and art of memory on the same character. I would probably allow remembering casting tablets and some of his master's lab notes in that context.
I feel like this is one of those virtues that was just brought as-is from previous editions and, while I forget the rules for lab texts in previous editions, I think it might have been useful once but not generally useful anymore. There are probably some edge cases where it is quite useful, like the aforementioned itinerant or a person whose lab explodes every few seasons but, in general, as written it saves 1mp per year and no time. It should probably be scrapped or given some other bump and I think "remembers the lab texts of your parens" might be a good one. To be determined what the exact mechanical effect is but sounds fair to me.
There is no errata for Magical Memory, and except for a few niche situations it is indeed a quite weak virtue.
There are some cases where it can be quite useful, but those cases are rare. Like if your entire lab with all your lab notes burn down, it can be nice to be able to reinvent stuff without having to start from scratch.
An illiterate wizard will also find Magical Memory very useful since it means he can get the benefits of keeping lab notes even if he can't write them down. Illiterate hermetic magi are very rare though, so this is mainly useful for hedge traditions like the Gruagachan or the Folk Witches where literacy is not as common.
From what I recall of HoH:S, Flambeau was illiterate most of his career, including when developed inventing new spells, so this was probably the Virtue for him
Another possibility would be to allow the magus to study lab texts to commit them to memory, at the rate of Artes Liberales x 60 levels per season (similar to the process of copying lab texts). Those then become part of his mental library and he can use the memorized lab texts at a later point (to learn the spells or enchant the effects).
It now occurs to me that this might be unbalancing. As an apprentice, you might have helped your parens invent a spell 20 levels above what your gauntletted mage can cast. Or helped your parens create his Longevity Potion.
It would be luck of the draw if any of these "memorised" lab texts would be useful to the character. Though if knowing lab text granted the similar spell bonus...
Depends on what you mean.
That Flambeau the founder didn't learn letters until late in life does mean he was illiterate until that point, but afterwards he was not illiterate.
It does however not tell us much about exactly when in his career he learned to read and write.
Was it at 30 years of age or at 80 years of age or at some point in between? All of them are late in life compared to when people typically learn to read and write.
Well, I don't have HoH:S in front of me, so perhaps I am misremembering that after He founded his House, he needed tutors to teach his personal apprentices reading and writing. So I have it in my head that he was illiterate until after the Order of Hermes was formed.
While he did hire tutors to teach his apprentices Latin and writing, it doesn't say why he did so.
Perhaps he was still illiterate at that point. Perhaps he did know how to read and write, but wasn't very good at it so he hired tutors that could do a better job of teaching.
I don't know that it would be so unbalancing. Many of those would be out of the reach of the newly gauntleted magus, many would probably be somewhat useful (even if currently beyond them) and within the beginning specialties of the young magus. One thing I don't think should be the case is that the Player of the young magus selects them, it should be given to the SG or Troupe to decide based on the personality and specialization of the Parens.
I also like that this implies you get a free memory lab text if you help another magus (assuming you stick with the whole invention process) and provides further incentive to work with others.