At the end of the Matrix page, I see MIDI OUT 1-8, but I don't see any explanation about these in the manual. What is the function of these eight MIDI outs?
You can assign your Modifier (pedal) to the MIDI outs. This way the pedal can be used to transmit the set MIDI CC to other devices. The external modifier MIDI CC will be detected in the I/O setup > CTRL tab.
The connection would be FireworX MIDI OUT to next device MIDI IN, then (if you have more than one device) MIDI THRU to next device MIDI IN, etc.