Might be fine. It is easy to remove the plastic housing to inspect / dry it out, which I would recommend if you think water got inside or you saw bubbles come out. There's a battery in there that you would want to remove promptly if water got inside. I found that out after a 60min dive during which the little rubber overpressure plug popped out inexplicably and saltwater entered at some point (worse outcome).
Why you are dunking disconnected transmitters in water? Probably unnecessary. Just dunk the reg with transmitter attached, wipe dry prior to removal