Great, if a little impenetrable - UPDATE
Obtained this to integrate with AudioBus, which it seems to do fine. The documentation may assume you already have some familiarity with this type of processing, but the examples help a lot. I was able to filter out mod wheel and expression controllers that I didn’t want sent to some instruments, and limit the range of notes sent to others. Update April 2024 - I still think this is a great problem-solver. I used it for interfacing a keyboard which sends too many CCs to external gear, and I could block some messages and transform others to what I wanted. The example presets contain all of the techniques I needed (with some adaptation).