Sorry to not be as enthusiastic as I should but there is a remaining true disappointment for me : Reaper is still, at its 5.40 version, unable to detect RPN/NRPN MIDI messages for any action control.
An example of this : I have an Akai MPD32 with endless knobs that I am using to control cursor moves, zoom actions, etc... For this I still have to launch, before Reaper, OSCII-Bot with a dedicated script, this with LoopBe1 (virtual MIDI ports) working beforehand, and it's a chore : I had to make a WSH script to make all this more or less reliably working.
I was expecting a progress in this area since the days I setted all this clumsily with a great help from banned, gofer and Jeffos, three years ago (see
this thread for more details).