https://github.com/kmatheussen/radium/blob/master/api/protos... gives some clues as to what can be done with Scheme/python. I never tried the scripting back when I used it years ago but it looks pretty useful, on my list of things to explore.

Cakewalk has been scripted with a LISP (CAL) from the early days, at least through the 90s. I see hints that it still is but not sure with all the changes from Bandlab.

never tried Radium, but in Apple's Logic Pro you can write Javascript to do stuff to the MIDI as it comes in or goes out. I've found it quite useful. I once wrote a small script (at the request of another Logic user) that turned a monosynth that only supported "low note priority" into "last note priority." I'd be interested to see what Radium can do.