Awesome concept but, as others have said, I didn't really feel like I was being given enough information to make meaningful decisions. I think having something like traditional 'stats' would make it easier for the player to form a baseline idea of how strong a party is, and then all the class combos and experimentation could instead be used to optimise a party for more difficult or boss fights - it would also give the player room to experiment and discover good combos naturally.
Also, I feel like being able to drag the papers onto the quests to assign the characters would be a bit more intuitive a control scheme, even just as an extra option - sliding around the papers is neat so might as well make the most of it!
I really dig the presentation and general vibe of what y'all are going for here though, great work!