Yes, the platformer controls leave a lot to be desired. It was Sasha's first game and first approach to Godot, so he and I agreed that it'd be probably the best we would manage to get in the jam timeframe, and we needed to define the physics variables to start building the levels (if we changed the values we would've had to change the design).
As for the screenshake, I'm wondering how could be implemented to improve the difficulty curve. Can you give me a hint on that?
Coyote time: I dindt know the term haha. You are right on that and we wanted to, but weren't able to implement it.
cheers!