Hey, Alexey, thanks for chiming in. Now I know I'm not alone in this (MIDI) world ;-) Any idea you got I'm happy to help following up and taking further!
I really do wonder why there is no simple, generic, customizable VST/GUI for that out there?? I have tools like that for the Roland INTEGRA (it's even a free one) and the Waldorf Blofeld (paid), but either of them is awfully complicated because literally every single option of the hardware is represented, spread over numerous pages ... and these must take ages to program and test ...
If I could have flexible number of knobs (~10 of them), simply assignable as in the FX chains, I could control my external FX like native VST plugs ... ideally, if it would read the instrument definition to get parameters and CC numbers, I'd be a very happy camper