Hello there don't get to stressed we will get them back to health
1st make sure humidity and Temps are In a good range 71 to 79 degrees and 64 ti 72% humidity
2nd stop getting the plant itself wet only water on the very edge of the pot and do not spray the plant itself
3rd 100% sure you gave them to much nutrients your going to have to wait till ymthe soil is super dry and if the plants have not bounced back you should flush the soil with a few gallons of reg water ph between 5.8 and 6.4
Make sure you get a ph reading on the run off water aswell just to make sure you soil ph is in range
Just be patient it's gonna take time to recover.
If you have a bunch if seeds exyra maybe start some new ones now and have them ready just encase those die or maybe the new ones will end up passing them in growth
Just make sure you don't go and flush the dirt untill the soil is dry because they have over water damage aswell so flushing the spil b4 it being dry will cause more damage
I would only flush b4 the soil being dry if the plant really turns to the worst and seems like dlushing needs to be done right