I would again stop using the nutes, a little mistake and your seedlings are gone.

What's critical in this phase is simply to keep the rapid rooters or whatever that is in the middle moist. By moist I mean if you were to soak one in water, and (without a seedling in it) squeeze most of the water out, not all, that is a perfect environment for a seedling.

Also, seedlings need super high humidity. So get a dome and put them under it. Keep the light high enough that the rooters don't dry up.

Don't worry about the temps. There is an "ideal" range, but this is a weed. It will root in 90 degree temps too. Stop worrying about the calmag. You're 2 weeks away at least.