Still not really seeing a problem, to be honest.
If a covenant has a specific room where people can get healed up super-fast then they've just created themselves a story hook as word gets out of this miraculous room.
I'd far rather have someone make it and generate stories than not make it for gaming-the-mechanic reasons.
I've been thinking about the balance between story benefit, the goal of fun, and trying to maintain a power balance of sorts and I'm coming around to Trogdor's view a lot more.
Structure, Boundary, and Room tailoring really are not unbalancing. Let the magi do it.
If they are spells to designed to affect the structure, or room, sure. If they are spells designed to affect the individuals in the room, and you normally require those affected by T:Individual and T:Group to be present, then it is unbalanced. I can see that spells that affect things that one would normally find in the room or structure, inclusive of the room and structure might be easy to design a spell that affects those things without warping. Magi can gather a magical sense of the place, and tailor their magic to it. But people? Not so much.
Depends upon how you strike the balance...
The point is that there is no point in making a stat boosting spell with a month duration, because it won't save on vis. Now a room with under magnitude 30 which can be cast every couple of weeks and act as a recovery room is another matter- provided you keep the final magnitude down...
But we know that a magus can gather the magic sense of people if he caters a Group target spell to those people. Why is it different when he's designing a spell that's a magnitude higher?
That came off less clear than I had intended.
If you've tailored something to a structure, it's to the structure. If you tailor something to people, it's to people. You cannot, IMO, tailor something to a structure for an effect that affects everyone within the structure. The structure and the magic have no idea of who is inside of it. IMO, if you have an affect that is tailored to a structure, it should be something that really does affect the structure, somehow, and it doesn't warp the structure. So, CrCo spell that adds +18 to healing for R:Touch D:Moon at T:Structure (50th level spell), IMO doesn't really speak to me as something that is being tailored to an individual to avoid warping, but seems more of an end run around the issue. I have this spell that if cast on this building/room it doesn't warp the people inside. Uh what? It doesn't seem to make sense to me. If it did something to the actual structure, a Terram or Herbam effect, yeah, that's reasonable to not cause warping to the underlying structure. For the corpus effect, T:Structure isn't even affected by Corpus... Is that any clearer?
Why does the structure have anything to do with the true recipients of the spell?
That's not strictly RAW, as:
By definition it is everything within and the structure itself, so the magic can be designed to target specific aspects within that definition. The magic affects the people inside not as a side effect, but by the implicit definition of the Target. I don't (any longer) see it as game breaking to allow a spell to be tailored for specific people within a specific structure.
I still think there should be a control or limit on how many people can be included in that tailoring.
e.g. I'd allow a spell for a council chamber so that the current defined members of that council are not affected. For much larger amounts of people I'd rule that detailed interviews and time must be spent for each to allow them to be included in the tailoring This would not necessarily change the time to invent the spell itself, but would be a research-ish activity.
We are beyond RAW. We are dealing with what is reasonable. A structure cannot fit within a lab, therefore one cannot design a spell for a structure that doesn't cause warping. 
Thats an illogical stance - as a T:Structure spell can be designed in a lab. Totally agree we're beyond RAW, that's where the fun is. 
Well, we are talking about what can be customized, and IMO, one can only customize a spell to an individual, group, whatever if it can be contained and examined within the lab. I'm fine with a non warping spell for T:Structure or Room, because I can rationalize that the magi is going around and measuring the structure or room, but mundanely and mystically. But the things that the Structure or Room doesn't contain aren't really covered by the same level as not subject to warping, if they are affected by the actual effect. To put it a different way, if you are using T: Structure for a R:Touch, D:Moon, Guideline to aid healing by +18, you aren't really designing a spell for the structure, so much as you're designing it for people. And for the people, that's better represented by T:Individual or T:Group. A corpus spell with T:Structure doesn't really affect the structure, just the people within. And if your spell is customized to the structure it seems a bit of a cheat to say that when I cast this spell on this building I can greatly improve the healing ability of anyone without worrying about warping because they are in that structure. Does that make sense?
Yes, I know that RAW means that it affects the structure and everything within the structure. Yes I know RAW allows a magus to create a spell that is T:Structure. My hair splitting is that one can't really customize a spell to a structure without fitting it into one's lab. Here is one instance where I agree with One Shot, customizing is pretty much spelled out by the Longevity Ritual rules. I can stretch it by saying one can do it on a T:Structure or T:Room, but it doesn't apply to all of the contents, or at least only the contents that were present at design time. One doubts all of the people the spell above might be cast upon would be in the structure when the spell is designed...
I started from a very similar position to you JL. The reason I've relaxed my stance is really because I don't see the application as significant in the setting or in terms of game balance. A healing room, or an artificially calm council chamber seem like thematically appropriate spells. Sure there is a point at which it can be abused, but I'd rather allow it and warn the player against abuse than say no. The magic stat boosting spells are part of that edge case for potential abuse, but still isn't really abusive in concept.
Although who is really going to design a spell which is Structure and also spend the time to define it for every other wizard in their House. A player could argue that it is possible, but I'll kill the idea 100s of included people without additional time invested. And if they did, wow, that's years worth of great story potential. Let the poor magus have their powerful vanity project, it is no more breaking that many other activities.
I'm more inclined to just ignore Warping, because it's not worth tracking for bookkeeping, and only apply it for constant effects, stat boosting rituals...
I still think that the real limitation in designing a spell for (a) specific target(s) is that you have to know the target(s) ahead of time. You want to make a healing chamber spell and define it for a bunch of people and a particular room, go ahead. But inevitably over the course of a saga someone new will arrive. And since they weren't included in the initial design, they will be subject to Warping. Worse yet, you may move to a different covenant. Then all the people and the room are gone.
Also, you could design a level 30 spell for a single person, a level 35 spell for 10 people, and a level 40 spell for 100 people (in theory). Upping the level of the spell is a significant burden in designing the spell. Assuming this is a spell like a healing spell that you really only intend to cast on one person at a time, you've gone from developing a level 30 spell to developing a level 40 spell (with all the difficulties that entails) just to include more people in the exemption from Warping.
Perhaps we should instead make it that base 30 effects cause warping, rather than 30th level spells. Take a 25th level spell with T:Individual, and you increase it to T:Group it becomes a 35th level spell, but all that has happened is that the increase is due to the increase in the Target. Any actual warping effects of the spell, one would think, would be diluted over the entire Group, right?
Is the Hippocratic Staff from page 98 (under Zenodochium Items) of AtD relevant to the discussion and what is RAW?
Yes, both the effects in the staff are those style of effects which could be tailored to avoid warping.
That's a nice change and makes a kind of sense. I like it. It suits the enchantment power limits for rituals too.
Kind of similar to how I like to use the base effect to determine the raw strength of a spell power.
e.g. a Base 4 effect to move something is "stronger" than a Base 3 effect, regardless of how the R,D,T is then altered.
Rituals I'd be less inclined to change, even though it means having two different systems. The reason being that doing big targets and durations on 'relatively' low level effects can have huge impact, even if you're going with D: Moon and T: Structure. If you set the base target at 40, you could do level 35 base effects with a final spell level of 65 that isn't a ritual. If you set it lower, you start excluding a lot of R: Personal spells that are critical to some concepts, meaning you'll see magi who use shape-shifting or who throw lightning bolts becoming untenable; we'd probably end up with everyone becoming a DnD magus.
From this, I'd be similarly disinclined to change warping simply because its now using two different values to measure spell (base level vs. final level). If you wanted to house-rule it, I'd say go right ahead. But for something intended for RAW or similar I'd not want to add even more complexity; the game has enough.
If I were going to rework warping, I'd do it thus:
Warping for constant effect: fine as is.
Warping for powerful magic: anyone affected directly by a ritual spell that targets them (e.g. a corpus spell on a person) gets a point of warping for powerful magic. If the spell isn't a ritual, no warping is incurred. No immunity for being the caster of the spell either.
I might also be inclined to rule that any spell that has R: Arcane Connection or that deals in arcane connection range within the spell description (e.g. Leap of Homecoming) be a ritual, too.
Threadomancy from August but really I've been away for about a year so I've missed a lot, my apologies.
Target bloodline has specific allowance for not warping a specific bloodline in its core book description
The fact that there is such a statement in the description of target bloodline and no such statement in the description of target group implies to me that making a spell target group was not originally intended to allow you to choose 10 warping protected targets when the spell is invented. (Most likely David and the play testers didn't even discus the issue, so my deduction doesn't really mean much even if it is correct.)