Hi kaafirookie, Thank you for letting me know!
I can see now that the first hint isn't very helpful, I'll add more information to that hint with some other minor tweaks to the game in a post jam patch.
For now though, the first puzzle involves an caesar cipher, with a key of 3, [so for example A = D], the letters in the books need to be put though this cipher [the number with the letter is the order the letters need to be put together] then turned into numbers based on their position in the alphabet. [for example A is 1]. Solutions to puzzles are to the right of the exit, as a note on the floor, in case any other puzzles don't have good hints.
I hope the hints for the other puzzles are good, though if they are not, let me know if you have any more issues or suggestions.