With this mod, boat steering is so sensitive it's basically impossible to use them. Could we have an option to reduce sensitivity of the stick specifically in the boat, or to tie boat steering to the camera instead?

Unfortunately boat steering uses binary input, so making the boat face towards the camera is not possible. However since you brought this up, I did discover a bug where a boat turning fix that is already in Controllable did not apply to all types of boat (like chest and rafts). I've now patched that in 20dbbc7

Thanks for looking into it!

A new release is now available for Controllable on 1.21.1 and 1.21.8 with the fix