My memory issues make short, knowledge based games like this great! I can start again every few months, looking through everything and watching as the early stages become better.
A note, though: One of the hints mentions yin nodes, but it only specifies which nodes are yin or yang once, as far as I can tell. I think using consistent language (instead of alternating between major/minor and yin/yang) could be helpful for the learning process. This might be easier if the grimoire contains the hints and the text for spells!
Another thing would be tracking mishap dialogue in a separate "page" of the grimoire, perhaps near similar spells. (such as the 'fat cat' and 'skinny cat')
I know this is a lot of suggestions in one comment, BUT!! Arrows pointing to hints you get from one spell could be nice. Think the rumor system from Outer Wilds. (Second time I've mentioned it on this game, haha)
Loving how this is progressing. I hope you keep updating this more!