hmmm... I think I royally stuffed myself over. I forgot to check the library early on and now I find myself with only a handful of missing library books now that I'm at the final dungeon. I searched high and low, but all the secret caves are empty. All book spawning opportunities turned out to be meteorites.
I have seen nowhere discussing this book finding trouble. So it appears that I've been fated to a world where I can never 100%, so alas I must start over again.