Have you had the transmission fluid and filter changed before ?

Yes around 20k miles ago Mackenzie's Glasgow

When i did the 80 degree mod i found mine a real pain to bleed properly, my auxillary water pump bolted to the inner wing doesn't work either and I'm guessing the valve needs new seals also.
I went into the hidden menu and even though the temp gauge was staying in the middle, i could see the temp was getting up to 115 degrees + and my oil light was flickering on idle.
When i burped the pipes while bleeding with the front up on blocks it got a load of air out, i probably spent 1/2 hour or more doing it, the temp then stayed around the 90 degree mark.
It might be worth looking at the hidden menu temperature and seeing what it is actually doing.
When i rebuilt my transmission I replaced the oil cooler pipes, stat and cooler.
Another common fault is the main radiator that feeds the oil cooler blocks at the bottom but i have a feeling you have changed your main rad.