Prog Change have to be sent just before the end of current pattern, not a the beginning.
Can’t your Deluge be slaved?
Can’t you send Prog Changes just before the end of the pattern?
Some workaround with midi processors, which can map a note or cc to a PChange.
While not a solution for live jamming, you can fire off a program change a fraction early in the arranger mode of the Deluge. I have this working with my Deluge and various Elektron boxes. For live program change not in the arranger mode I had to give up and just get used to manually pressing the Elektron box first followed by the Deluge to change at the same time. You get used to it and it becomes second nature. Share your frustration.
I wish I could do this but thank you for the suggestion. I sing, play guitar and keys for my work and trigger arrangement parts with a Behringer FCB1010 through the Deluge. My hands (and mind) are on other things!