I mentioned TinyDB because it is local, and returns immediate results.
Firebase would require initiating a read of the SENSORS key and adding event blocks to intercept the incoming SENSORS value and adjust the display.
These are the blocks where you ask for the SENSORS value:
Had you been using TinyDB, you could have gotten the results immediately and set your text color and location sensor enabled attribute.
But if you use Firebase you would need to grab the SENSORS value after asking for it in those two event blocks.
Seeing how you are using the Location Sensor, be aware that screens are separate programs, and switching them breaks connections to Bluetooth and GPS.