One thing I noticed, you’ve got clear cups with a darker sleeve cup over them which is good to protect the roots from light. The more air that moves thru the quicker the soil will dry out. Do your sleeve cups have plenty of air holes? Where are the air holes? With homemade cups and holes in the bottom you still don’t get air moving thru the cups, can you elevate them safely? Like on a piece of rabbit fence or chicken wire fence, an oven or grill grate... place the grate on wood blocks or cans of soup... anything to get more air under them, position a fan to blow under the cups.
A while back I had some slow growing seedlings so I changed my process and cut bigger holes in the sides of the cup near the bottom. Most cheap nursery pots like shrubs or flower pots have holes in the sides not the very bottom... see pic