Through trial and error and experience, I know that the thermometer (Thermapen) inserted into spots at the top of the mash will give me instantaneous results that will line up with the thermostat of the Anvil Foundry control panel eventually. Recirculating the mash gets the thermostat to the correct reading much faster, but I just don't worry a lot about it anymore; there is no problem using the Thermapen to confirm actual temperature (as long as I get the Thermapen back to my wife's storage location in the kitchen after using it).
Before adding the grist, I have to remember to adjust the set temperature to the proper mash temp, too, as it will otherwise engage the heating element during the temperature drop from strike to mash.
I asked the manufacturer about re-calibrating the thermostat, but it is not adjustable (and as stated, it eventually reads correctly).