Over here that system would not have met code. A 2" drain is rated at 6 gpm and if each spray is rated at 2 gpm so you have 8 gpm draining just from the watertile and if you're using the body sprays at the same time, you are attempting to drain 14 gallons per minute through a drain that can only drain 6 gallons per minute. You need a minimum 3" pipe ALL the way to the sewer.

In addition if any other lines, like the sink or bathtub, drain into the same pipe you could exacerbate the problem.

All I can say is you'd better be careful the water doesn't overflow your shower pan and cause real damage.

And is your water heater big enough to give you enough hot water. At 14 gpm you could get an almost three minute shower from a 50 gallon hot water heater, maybe 5 if you mix in cold water.

LOL but DH would die laughing if he could see the things I've needed to learn to remodel our own bathroom including the dream shower he wants

That will never pass inspection if you go to sell. It's a flood hazard, and if you have an issue, it's doubtful your insurance company would pay a claim because you deliberately violated code. Get rid of the ceiling watertile and you will probably be fine.