Been a while for me messing up watering but I don't think the soil was too dry because usually you would have yellow / dying leaves and an instant recovery after watering. I believe you are over watering which yields what you are looking at there. I can make that call by your photos and what you said. mj very much likes a wet/dry cycle. It's like diving into a pull and holding your breath, you can do this for a short time. The root system needs air also it doesn't pass oxygen down to roots that aren't receiving enough oxygen. So you wet the soil thoroughly then let it dry until the planter is very light (but never so dry that the soil is cracking / pulling away from the sides just very light). Too much water per watering = gnats, not enough water per watering = water stress. No dry cycle = your plant symptoms
Keep the air moving in there but that huge fan shouldn't be pointed directly at the plants at that distance. Point it at a wall let it reflect back gently but persistently to help the plant throw away water. (I think you already do have it right because the fan is the same in all the photos, just making sure) They will be ok this isn't a huge setback just get the watering down to a science.
gl