I'll try to give some blind tips here that might help :) (I think that stage of the game is balanced okay)
- Dungeon 4 enemies skyrocket in XP gain, so getting further in is really beneficial for Squire. Might will eventually overtake Wisdom in how quickly you gain it.
- If you're missing anything that will power up XP gain for the Researcher itself, I would focus on that if Squire doesn't seem to be leveling up fast enough. Faster XP on Researcher means faster Wisdom gains which means faster XP for everyone :D
- If you're missing any achievements, those can provide some nice passive bonuses too. If you're missing secret achievements especially, check the discord as all the answers are there.