some thoughts of this game:
the presets didn't fill right (e.g: celeste's down gravity is too strong)
double jumps seems broken (you cannot do 2nd jump if you didn't do the 1st jump, sometimes 2nd jump just misses)
if you turn on the lookahead, I think the camera's position should stay still when you don't move (instead of returning to center)
You should add the offsets of the camera (because many games mainly go rightward)
And I have no idea how to implement this into a real game. I'd be appreciate if you share the source code (especially the character movement)