I've run a full frame bag on my touring bike with exposed cable for ~10k miles. This has rear brake cable exposed between cable stops on the underside of the top tube, and exposed front and rear shift cable on the down tube. All three have Ritchey couplers (S&S couplers on the frame), so the coupler for the rear brake does move a little between the top tube and the top fabric of the frame bag, but it's fairly loose between top tube and bag. (If you have a frame bag with laces along the whole top edge, you might need to take care not to lace it extremely tightly.) The shift couplers just move in free air below the down tube.
No problems to report. One does need to take care with any velcro straps -you want the strap under exposed cable, not over - but with housing it doesn't matter. And I had this bag custom designed to this bike - between the cable stops, cable couplers, and frame couplers, it's a little fussy about where the velcro straps should go. Plus at the time (2013?) there were not many off-the-shelf frame bags yet.
Custom bags from small makers are the same price or cheaper than ready-made ones, so this shouldn't deter anyone reading this post. It's usually quite simple now, you just upload a good quality photo of the frame, with a ruler or tape measure in the photo