Usually when I have to deal with wilted seedlings,it's outside. Maybe we had too hot of a day and they need extra water. Or I didn't harden them off long enough. But this year I'm having the issue indoors. We've been so hot indoors lately that they are acting like they're having issues from not being hardened off long enough. Problem is they're indoors. It's just too hot inside for them and I don't have ac in that part of the house, so there's not a lot I can do (only in the bedroom).
I'm considering moving the ones most affected (cucumbers and eggplant) into my bathroom in the evenings and giving them some cool off time.
I'm looking forward to the day when I'm in a house that stays cooler or has something like a basement that stays cool. Then the poor plants won't have such a problem when the house is unusually hot. They were doing great until it got hot inside.