Transforming Mythic Europe has a lot of new book rules. The large library rules might help for mundane collections but I don't think will work all that well for most arcane libraries. (For each skill or art the library has an ability and quality score with a base equal the the summa with the largest ability+quality total. Every additional summa gives one XP in the libraries ability score, which increases like an art. Every additional tractus gives an xp in quality. A magus gets Quality +3 xp up to the libraries ability level and then quality thereafter, for a maximum number of additional uses equal to quality. Tracti must be within 3 levels of the libraries quality to add to it, Summa within three levels of level+quality).
Since the rules say that, to provide XP, a text must be within 3 levels of the current library score, any one text will provide library XP sufficient to increase the libraries score to text score +4.
I really like how easy these make library book keeping easier. I especially like the idea of using these rules to model how a library grows.
For mundane text one pound buys one XP in either an ability or quality. Maximum ability level is likely 9 (Level 5 Summa + 4 levels). Quality, assuming sound traci, maxes out at 15 (tracti quality 11+4). In most instances, the new library rules starting with a high quality text as a base and adding summa to raise the ability score. For example starting a library on Artes Liberales with Ars Grammatica (Ability 5, quality 15) and supplementing with 30 additional summas on Artes Liberales (which probably does a good job of modeling a descent monastic library on the subject). This would cost 30 mythic pounds (a year and a a half's income from the average manor) under current rules.
(Note: These rules really seem to fall down when faced with Ability 2 / Quality 15 primers. This gives a total of 17 points which edges out Ability 5, Quality 11 texts, this can be solved by using build points costs instead of ability + quality).
Arts are more difficult. Costing their level in vis, it can become prohibitively expensive to accumulate 15 or 20 summi on one art. Legendary texts have a score + quality of 35, meaning that they cannot gain xp from score + quality 31 texts (while glossing a text could help with this, sound treatise already assume some very high art and com scores). A summa with a score of 15 ability and 16 quality will be hard to improve on with tracti, and would tend to penalize summas of higher quality. (And also disparage legendary texts as both an ordinary and legendary text maxes out at arts level 20).
So, after looking at the numbers, the large library rules seem like an excellent way to handle mundane collections. For an arcane library, you are probably better simply saying that all tracti are either Q:11 or Q:12 and just keeping a count of the number of tract of each type possessed with a cross check against the number of tracti read on a character sheet. A covenant gains two tracti per year in trade per each pair of scribe/illuminators with maybe one book binder required per 20 volumes a year.