In our campaign we have found a cache of formerly hermetic books that a mundane scholar has scrapped clean and written over. Since our covenant is suffering from a book shortage and the SG takes calf and cow very seriously we would like to restore these books.
In 4th Ed., I'd have told you to find out how old the books are and, if they were within range, use "Eyes of the Past" on them combined with Intellego Imaginem (Animal Requisite to peer through the pages without opening them) to see what they looked like before they were written over and then do a fast imprint into new books. It's Rego/Muto Aquam to cause the prepared ink to flow into the correct configurations, then transform into their proper "fixed" state; Terram Requisite if you wanted to add illumination. Far faster than copying by hand, but needs an Intelligence+Finesse check of 9+ to make certain everything is exact.
I'm still learning 5th Ed. My instinct would be to consider the feasibility of an Arcane Connection in a Creo Animal/Aquam/Terran Ritual to "heal" the books (Group Target), pulling back together all of the components that belonged to it when it was an Hermetic work, in the correct configuration.
A related strategy, if you have the name of the author and the book to be restored, is to use the Creo Ritual to attempt to call forth the 'ideal' copy which must presumably exist in the Realm of Forms. Whether it existed before it was written or only after is open to debate, as is whether the "ideal" would be a copy of the original manuscript or the palimpsest you have in your possession or a hypothetical "ideal edition" which can ONLY be brought into the world through the Creo Ritual and not through actual writing or copying. The book, the name of the original author, and the name of the book are all potential Arcane Connections to the "ideal", allowing the Ritual to take place.
In all of these, it'll cost you Vis to get the books back. Very specialised Intellego Aquam/Imaginem/Terram (Animal, too) to detect the old patterns on the book pages might not take Vis, but it will still be laborious. Maybe add Creo Imaginem to make the old patterns glow on the page, not unlike the method being used to read the Archimedes palimpsest in RL.
Mmmm. An InAn(He) (the requisite being for oak-gall inks) spell should allow you to see the past state of the books, and with that you could then scribe copies. It'd be slow, but worth while. An item with a similar effect, given to a companion, could be used to examine other books to find out of they're worth similar efforts.
Scraping a book is not perfect. The pages are still stained by the ink used. The intellego requisite is fully capable of identifying the old text. (Though it might require an extra magnitude or two for the complexity.)
If no copying is allowed, due to the calf and cow oath, your only choice is to make the book "heal". An example spell from the spells wiki:
Recovering the Damaged Tome
CrAn (req: He,Te) 60 Ritual
R: Touch, D: Momentary, T: Individual
Repair all damage to a single written tome.
(Base 35,+1 Touch, +2 Treated or Processed Products, +2 Requisites)
Contributer: Ed Campbell.
Notes: I included the herbam requisite for the board used in the cover, and both the terram and herbam may be required for ink repair.
I think such a spell could restore a palimpset to its original state, as the original writing still exists (it was not scraped off completely).
Another possibility is using magic to highlight the underlying text, with InIm as mentioned above. This should suffice to read the book as normal, IMHO.
If you can copy the book, it would probably be easiest to use the InIm spell on a mundane for a season (or year or whatever) and let him copy the books manually.