As you know very well, MONO modes are made to prevent two notes sounding at the same time, and therefore any new note kills the old one.
But do you know if it’s possible to set up a MIDI Input Transformer configuration (or vst plugin?) which enables the user to make the passing thru MIDI notes stream MONO…
by eliminating all incoming Midi notes which are played while the currently playing one is held?
A kind of “privilege of the still active elder MIDI note”?
If not currently possible, then I make it a feature request!