I have wired 2 thermostats to control [1] the bedroom and [2] the kitchen. I switch between them with a rotary 5p2t switch. But I can't easily tell which thermostat is getting power and controlling the system. I'd like to put some led indicators next to the switch with say, blue for bedroom, red for kitchen, or at least one light for the bedroom since the switch is in the kitchen. Can I wire a 24vac led pilot between R and ground or will that in anyway disrupt or short the circuit or damage the air conditioner transformer?

You may need to get a common wire there,
You could also have a neon light across each thermostats contacts, when it is Off, the Led is ON, this needs no Common, or ground.
I can give some better info, but need you to more explain your set up, Why not just have separate thermostats for each area.
Do you only select one or the other, or do you also need the ability to use both.
Do you only have enough existing power for 1 unit for 2 areas?

Thanks for your response. We have a single AC that is on a zone that heats/cools the kitchen and the upstairs bed room. Originally the thermostat was in the hallway to the kitchen. This did not make it very responsive in the bedroom. So I ran a thermostat wire extension from the hallway to the bedroom and added a new thermostat there. For the time being I have disconnected the hallway thermostat, but it is still in the wall. This is much more comfortable in the bedroom. But since there are times when running the thermostat from the hallway also makes sense, I purchased a 5p2t switch that I would put in the hallway so I can choose which thermostat to use. I thought a light on the switch would be good. So in essence my plan does not call for a common wire, but rather all five inputs switch from one thermostat to the other. The AC works fine in cooling both areas. It is just that the thermostat needs to read in one place or the other, and I'd like a quick indication of which thermostat is in control.

Hope this clarifies the situation.

You will need a common wire and you need a wire or two to each thermostat, so at each thermostat you can tell which is active.
I'm like Ronco, "I set it and forget it". If temp is fine why the checking? Feels hotter than it should be?