Ah, now we're getting somewhere!
It looks like your StudioMix device sends completely different MIDI messages than for other users: it doesn't seem to be sending any NRPN messages at 14-bit resolution (see
post #3 and
#4 at the beginning of this thread for the StudioMix configuration that this script expects), but note numbers and 'plain' 7-bit CC#s. That's quite different, and explains why you didn't have much luck using it yet.
Perhaps what I said above was wrong: maybe the StudioMix device *can* be configured to use different MIDI messages after all?