Hey Dave,
Cantabile definitely does process poly aftertouch, but not in the Controller Map dialog (won’t work, that one is just for non-note-specific commands, including channel pressure). There are other filters that apply to poly aftertouch, like “velocity curve” or “aftertouch to controller map” or “suppress events” - these work nicely with poly aftertouch.
But converting poly aftertouch to e.g. notes will probably require a little reaJS script.
Cheers,
Torsten