Where are your airstones?? water should be below the rooter plugs,depends on how much agitation you bubbles make

why change from 3-2-1 to 2-2-1 ?

little roots like that only need 200ppm, but right now they need flushed for a few days.
lower water temp to around 65F, let the plgs dry a little for a while,but you need to keep the roots damp-wet
need to raise the humidity,try misting every few hours. not sure about using a dome
hope this helps,good luck