they don't care what their orientation is. It's not smart to do that, but it won't effect the functionality of the equipment.
Problems with reversing
Muscle memory says valve is on the right, knob is now on the left if you jump in with your air off or need to shut off/feather the valve it's backwards.
The regulator has to be flipped upside-down for the hoses to come out properly. This means that your regulators are now backwards for lost regulator recoveries. Primary is now in the back
This also effects the position of the hoses, most regs have the hoses pushed somewhat forwards, so now they are going behind you and back forward. Not the end of the world but an issue.
Depending on how low you have your tank positioned *most everyone wears them dangerously low*, picking the rig up may be an issue. A DM may not be able to reach the valve to haul you up or to help stabilize the rig etc without grabbing the first stage. This means that the yoke can slip off. Same if you have a bad entry off of the boat, it may knock the first stage and pop the whole thing off, rare and unlikely, but it's there.
Depending on the regulator you have, it may be better to just buy the yoke conversion and make nice with the show/dive boat operators and see if they will swap if over for you if you aren't comfortable doing it yourself. It takes less than a minute and is a much better option that switching them over.