If these were my seedlings I would hit them with a good seaweed/kelp feed, along with some alfalfa tea and something, anything, that will help start a microbial culture at the root zone. I think I mentioned that I've only ever started seedlings in soil, I must admit, starting a new seedling in coco seems like it could be problematic, but it's time to get that experience under my belt now, isn't it?
Now I can't remember what the RH & temp numbers were you posted up, but I remember *that* you worked the VPD calculator and came up with a number that seemed off.. (sorry, been a long day and I've done a few bong hits), and my suggestion is to not worry about the numbers, play with the ranges (of temp and RH, but don't let temp get too low, that stalls seedlings) and see where they tell you they like things.
I remember someone asking me about what I meant about how I water seedlings. I put them in beer cups filled with a light soil mix after I have a tap root (the dreaded paper towel method!), put those onto a tray, fill that tray with about 1/2" of water. Because the soil is well amended I don't need to feed *or* transplant until they're falling over in the cups, which is also when they're rootbound which is also about when they begin to alternate nodes and show sex. Once they're transplanted from those first cups they begin being watered and fed like grown-ups.
