I think I'd do things a little differently.
Not really thought-out, but I'd probably have something along these lines:
Level and Quality are considered as per the Abilities XP table.
Tractatii add their Quality to Library Quality, twice that to Library level.
Summaes add their quality to Library Quality XP, and twice their level to Library level XP. Realia work as summaes.
You might want to lower quality XP, but you get the idea. This represents that you can study from multiple sources, and that even a Q10 summa may have insights useful to a master of an art.
As an option, if your art level is > Library level, yu can still study from half quality, scrapping bits here and there. If it is twice that, yu've read everything.