It actually is quite easy. It works the same way you did with the volume.
See the $ENGINE_PAR_VOLUME as adress within Kontakt. So you just need another adress.
I do not know them exactly atm but there is a huge list in the KSP-reference with all the
controllable parameters in chapter 21.
So you just need to insert your prefered reverb in one of the instrument- (serial) or better send-fx-slots (parallel),
copy your “on ui_control” and change the adress ($ENGINE_PAR_abc,x,y,z). don´t forget the internal routing
when working in parallel via the “Sends” If you do not want to alter the reverb itself, you can just connect the
reverb-button to the send-level.
There should also be a tutorial-video from David Hilowitz…