Hmm, does not look like the G-Major had an FXLoop…. At least from the grainy picture I just looked at… So that is not an option…. Sorry.

I know that the GCP can not send Midi cc's from PC switches, and vice versa.

I have seen midi devices, little boxes, that can listen for a specific MIDI command and then translate that on as a different command, not used them myself and I have read they can be difficult to program but once you have programmed it I doubt you would need to change it that often….. Let me see if I can find it…. As I say no affiliation or recommendations given