well i dont think misting is needed, unless your foliar feeding. Definitely dont mist with lights on. But I guess it wont hurt but not needed.
I agree that could be too much fan as well. But if your using ro and not adding cal mag that is likely the problem. Although now that fan/wind damage was mentioned it could be that.
I dont know much about coco, im a soil guy. The tricky thing is once the big fan leaves have damage like that you cant make them healthy again, only try to stop it from getting worse. But you can still flower them and probably get a good end result.
Possibly even heat stress. Better to have the light a bit too far until you know for sure where the best level to have it at is.
Since the light level and fan speed is easily changed and shouldnt have negative effect, Id do all 3 things (move fan so it blows above the plants at canopy level, not on the plants directly, move light up which I think you did already, and add cal mag for the next couple waterings then every other or every third from here on out).
80 is a bit high but not that bad, shouldnt cause issues. Watering once a day might be too much but it might be ok as long as they dry out a fair amount in between waterings, again Ive never used coco so idk for sure about that.