Kind of excited that I have figured this out and it is currently working (though not extensively tested) in my editor MIDI-MIS...

Tired of having your bass drum be just a plain ol' bass drum?  Tired of that same single note coming out of your cymbal?

I've figured out how to supplement my note adjusting code for easily transposing notes on regular instruments to now work with percussion!  It now can automatically add and adjust pitch bends and pitch bend ranges to percussion (entire track only, not individual note based), and I've successfully listened to a cowbell at a full +/- 58 semi-tones / +/-4 octaves.

Like everything else I've added to my editor, the current soundtrack I am working on for the SNES MIDI Remaster Project threw me a curve ball that required yet more ingenuity to accommodate.  This time around is note-shifted snares where the sample itself was dropped an octave, so the notes in the resulting MIDI file still play the un-dropped pitch.

Current functionality is limited to a single percussion instrument per track/channel, until I figure out how to trickle the pitch bends through to any other percussion without changing the perceived pitches when the bend range is altered.  Once I get it working to the point of being "complete enough", it'll get uploaded to my MIDI-MIS repository.

https://drive.google.com/drive/folders/114K2TuMGXu7w_vX-iBWI0Kf9RCb9wi6K?usp=drive_link

Attachments seem to be behaving oddly.  I can't attach more than one image, so I am attaching 4 screenshots and 4 cow bell files in a zip to see/hear.