I'm replacing a couple switches in a bathroom with smart switches and ran into a problem. The previous owner redid the bathroom and the switch box in question had 5 Romex cables (four 12/2, one 12/3) going into it. Only one of them had any sheath past the integral clamps (my understanding is there should be a minimum of 0.25 inches). When removing the switch box to see why I couldn't get any slack, I found that the rest of them had between 2 and 5 inches unsheathed before the box.
Am I supposed to add a junction box above it in the wall to splice all of the cables to add new cable that is long enough, raise the switch box 6 inches, or something else?
Edit: pictures added for 1. 2. 3.