I am several years away from hard synths and sysex, so bear with me. I assume your controller, and 6i6 is usb into computer, and hard synth receiving signal from 6i6 midi 5 pin output. Cantabile is your “DAW” so to speak. I’ve seen many threads on this forum about sysex being used in Cantabile to hard synths, so I know it’s possible with a correct routing setup. I suggest you do a search on this site for “sysex”, and I think that will get you started until a skilled sysex member chimes in, which will be soon. Other than that, check these out:
https://www.cantabilesoftware.com/guides/sysexMacros
Hope this helps.
Regards
Corky