Nobody's reported this because only we Americans use Fahrenheit. We're small in numbers as far as I know and it's possible those of us who are playing don't use Fahrenheit for the game or don't even know that there is a toggle to change Celsius.
When I view the current temperature before performing a practice lap, the displayed temperature is correct.
After I have clicked "Try Setup" and performed a practice lap, the temperature reverts to Celsius.
E.g.
Pre-practice run: Try Setup 50*F
Post practice run: Try Setup 10*F
(82*F, now reading 28*F)
CEO & CTO