Thanks for the details!
Even though ProTools shows the Track16 as a MIDI destination, the Pacarana is controlling the Track16 (not PT). Do you have a 5-pin MIDI output on your Mac HD I/O? Could you route MIDI by a cable from that interface to the Track16?
Another approach might be to use Delora software's Kyma Connect to create a virtual MIDI destination on your Mac that can forward MIDI to your Pacarana over Ethernet.