You may be experiencing the issue in the below threads (one of which is mine). If your thermostat can be set to "auto", I believe google home will be able to change the setpoint - but not if it is in heat or cool mode. Developers are aware of this - if not from these 2 threads directly then from a ticket I opened. As I am using Nest, which is mostly unsupported at this point in time, a fix is understandably low priority. I was able to get around the issue by linking my google home to the nest directly.
Sorry I'm not much help on fixing your issue as I know nothing about Radio thermostats, but it may at least identify the problem!
