Dreaded P0A80 Code - Car Running / Charging Good.

Mixing coolant is not good. You run the risk of it jelling up, and not flowing.
But it's done.
If you fill it slowly, and a little at a time, you won't have to worry about air pockets because the coolant
will push it out.
If the coolant temperature is within specs, while driving, it's likely working correctly.