You don't want your soil to hold too much moisture. Lots of problems are caused or at least exacerbated by overly wet medium.
Looks like your soil (s) are/were too chemically 'hot' for young seedlings. They may grow out of it or not, but they are pretty stressed... You'll want to flush with water at correct pH, make sure the ventilation and temperature in the room are correct, and go a lot easier on watering in the future.
If you have a 'grow' fertilizer with micronutrients, in about a week, make a VERY VERY weak solution about 1/5-1/4 what the label says and LIGHTLY mist the plant with this. I can't tell how many nodes you've got since it's apparent that leaves have alreaday dropped. Heck, you might be ready to do the foliar right away. Count... 5 nodes= ready to start lightly feeding. Those seedlings look locked out and hungry, but contributing to the existing problem in the soil will make it worse.
At next transplant, use MUCH more perlite in your compost mix! Drainage=good!