You need to figure out how to put the value from ‘percentage’ into the data your call services node uses to tell the thermostat to update… That page has everything you need to figure THAT part out.
But the bigger question - If Alexa told the thermo to do 20 and it did it you’re done - But you’re trying to do something else with the number - what are you ACTUALLY trying to do?
While the topic says thermostat, those are attributes from a light. I’d guess a light is misconfigured in mqtt and is sending it’s message on the thermostat topic.
Yes I believe the Emulated Hue & in NodeRed the Hue Hub don’t know about thermostats they only know about lights, unless you know otherwise and point me in the right direction.
Yes, the node you are using emulates a Philips Hue bridge so every entity is handled as a light.
I use it to control my thermostat. It is configured to simply call a script. The script confirms the requested temperature (received via percentage) is within a reasonable range before it attempts to set the thermostat’s temperature. This step could have been performed in Node-Red but I chose to have it in a script.