The docs say
During the production, a calibration is done at two temperatures (+25°C and +85°C, with a tolerance of +/-10°C(1)). At each temperature, the temperature sensor value Ti is measured and stored in EEPROM memory(2)and
Be aware that if EESAVE fuse is left unprogrammed, any chip erase operation will clear the temperature sensor calibration values contained in EEPROM memory.That does not really tell me where they are in the EEPROM, nor if they would have been erased by the time I receive a board containing a 32U4.
Trying to decide how useful the sensor might be, or not.