Fun game with some neat concepts.
I got kinda tired constantly retyping everything - you could implement a numbering system so you can invoke each spell by it's number.
The spell hints you get in notes are mostly useless past the first 2-3 spells. You should introduce some way of finding more hints - maybe reading the bookcases?
I finished the game but one part of the game was left unexplored it seems - the part with hot floor and two red buttons on each side of it, at the bottom of one floor, don't remember which - why was it unused?
Thanks. I would definitely make some changes like what you suggested if I planned to expand the game further, but I'm happy enough with what it is. I think it's fine for game jam games to have some rough edges, after all, one of the main reasons to enter a jam is to experiment with different ideas! I also didn't have time for any real playtesting during the jam, and I didn't feel like making significant gameplay changes after the fact.
The chest that portion would have given you access to was just a note showing the more obvious use of (rot13) YVTUGRA. I'm guessing you found the second note about it first and deduced the other use on your own.