Would the new MIDI implementations "MPE" (Multidimensional Polyphonic Expression) help and simplify expression mapping?
https://www.midi.org/articles-old/mi...expression-mpe
The specification:
https://www.midi.org/downloads?task=...ethod=download
(you have to register for this download to work)
MPE has been standardized this year (2018) by the official MIDI Manufacturers Association (MMA).