Your picture cleared up a few things
If you have a reliable temp gauge in your instrument cluster, that should be good enough. If you have access to an infrared thermometer, you can point it at the top radiator hose to get a more exact temperature reading after the car has reached operating temperature. If those are in reasonable agreement, I wouldn't worry about needing an overheat indicator.
My son's 90 325i convertible does not have the overheat text label in the active check panel (just seat belt and SRS). When his water pump failed and the car started to overheat, I got the check engine light and quite a few of the other warning lights in the instrument cluster to light up as the temp gauge started to tip into the red.
What year and model is your BMW by the way?