Thanks for the long review, I really like to read feedbacks like this, helps me see the game for another angle.
I admit that the cards are a bit OP XD. I'll try to balance the cards in the next update, I made the code in a way that if I want to change the cards status the saves won't be broken, so it's totally fine. I'll probably chance tashigi card to +3 in all stats or maybe +2, it's too strong if you have many tashigis stacked.
I have other plans to balance the game that I don't want to talk right now since still too early. but don't worry I'm aware of this problem, and I'm working on it.
Cheers!