How many months does it take for a HomePod Mini to calibrate?

Once upon a time, my HomePod Mini worked fine. It communicated well with my so-called 'smart plugs' which are nothing of the sort, and upon one of the iOS updates, it calibrated for both temperature and humidity. Now it only functions as Siri input device and a very expensive bluetooth speaker. I've given up trying to use it as a HomeKit home hub, but now after resets, several calls to Apple, and a trip to an Apple Store, it is still calibrating to set temperature and humidity.

My question is: how many months does it take to calibrate?