I found the missing book, but she does not give any dialogue to turn it in.
This is the version of the quest where you run around her basement looking through a billion book piles.
https://gyazo.com/f7de685167507e2cef7a1ac9f28e9f74
Yeah. I notice that, despite the buggy text, you seem to be able to turn in most variants of the quest between what she tells you to do and what you actually do, so long as you talk to her once or twice extra. With the EXCEPTION of when she tells you to go deal with rogue spellbooks and actually going down to dig through the book piles. That one's just impossible to turn in.
Had this today. Pretty sure all the quests are looking for the book, but the spellbooks one is looking for a certain kill, so if all you have is the book, no dice.
Today I had the "find the book among many books" one and instead I got the "thieves stole your book, but here, I found" it result and got 100 gold extra.
Related, the Stables quest dialogue very very very rarely matches up with the variant you get.