Hi everyone,
I know this is an old thread, I did my own reverse engineering of the swytch kit because the handlebar connector doesn't work properly and the motor cuts off when riding over bumpy roads so I'm planning on bypassing completely and find another way to connect the controller to the accessories. I'm documenting my findings here:
https://github.com/vladbalmos/swytch-pro-pinout
In case anyone else is interested. Besides the text documentation there's also a diagram on how all the connectors & pins connect to each other.