I have this question awaiting an answer from Kia tech in a little different format. There are two temperature readings on my GT2, the usual coolant temperature gauge on the dash, and the "Oil Temperature" readout on the LCD screen between the speedometer and tachometer. The little coolant temperature gauges on most cars are not very "accurate" in terms of absolute temperature, not to mention that they often have no numerical scale, just markings. I simply take note of the normal operating position of the needle on the dial of that gauge when the car is new, and assume with confidence that anything higher than that "normal" needle position is cause for concern.
The other LCD reading is unclear. Normal for my car is 200°F which is dead-center. But no one, including (so far) my Kia techs, can tell me if that is an engine oil temperature gauge (rather redundant with a coolant gauge) or a transmission oil temperature gauge, which would make more sense with a torque converter transmission being monitored during launch control conditions or power braking. I'm waiting for an answer from Kia. In the meantime, I'm sure the ECU will complain if it sees something it doesn't like.
I would suggest that the LCD readout is a transmission oil temperature gauge since it takes about 5-6 miles of driving to reach a stable 200°F where the engine coolant temp gauge stabilizes in less than half that time. Normal operating temperature range (according to my Kia techs) is similar for both engine oil and transmission oil, and we know that the transmission oil is cooled by engine oil coolant heat transfer on this car. Excessive use of launch control could push the transmission cooling beyond design limits even with auxiliary cooling and result in excessive temperatures which would be the reason for monitoring transmission oil.