Thanks! Glad you liked the game
The main bonus of a higher trait is being better at associated moves. Things are deliberately minimal/abstract to not overload players. (So, for example, Hermione casting a higher year spell would fall under the more abstracted Luck mechanic)
Of course, you're more than welcome to hack the game & add more complex mechanics. I'd love to hear how it goes! My only recommendation is to see how it plays as-written, so you can get a sense of what actually works & doesn't work for your group