First of all, this thing is a life saver. Had great times playing around with the program and the engine swaps.
The only thing I would suggest is that the power graphs in the UI should also be updated on an engine swap, it's just a few lines in ui_car.json (if this is actually a thing already, it does not work for me).
SUPPORTS_SHIFTER=1 ; 1=Car supports shifter, 0=car supports only paddles