I can confirm that Renoise sees but does not record or even transmit nonzero note-off velocities to instruments. (It sends every note off event with velocity 0. I am not sure if it’s actually sending note-on or note-off, but either way it’s sending velocity 0.) Some instruments respond to positive note-off velocities, so why not use the velocity column of a note off in the tracker to send a note-off event with that velocity? Here’s how I think it should work:
7931 