It's been a while, but I finally have an update to share! I finally had some free time to work on the script for the game and... ended up replacing the entire glossary system instead. oops
It turned out the one I had been using wasn't very good at accounting for duplicate entries, so if you used the back button you'd just end up with several of the same entry, which wasn't ideal, so I found a new one
I ended up using this encyclopaedia plugin, which is. way more complicated than I really needed (and took me a while to figure out) but it offers a bunch of sorting options and seems to more reliably keep track of persistence, which fixes the problem I had been having.
It did take a fair bit of wrangling to get the interface to match the rest of the menus, due to the base plugin being made of multiple copies of the same frame instead of one big background image, but I got it working after a lot of trial and error.
Here's a comparison between the old one and the new one:
I still have to figure out how to intergrate it better with the in game menus, since it is the only menu that doesn't show the in game menu when it's open, but that's mostly cosmetic so I can leave that for another day (I'll probably end up remaking the in game menu bar to be along the top like tabs anyway)