What does the "Cancel" button on the thermostat control supposed to do? I doesn't appear to actually cancel any changes made and it appears to just go back to the previous climate status page. Should that button be renamed "back" or "previous" or "ok"??

Cancel is the same as "back". It "cancels" out of the current screen... I tried to stay consistent with this but as I added things the nomenclature might have changed from view to view. I will review all and see if I varied that. But your "gut" feeling was correct.