Even the best Foxfarm Soil is not good for seeds, 'couse the fert in it it will damage the roots.
I'm shure Foxfarm and lots of other US-Brands are selling soil specially for seedlings, you may use any soil made for seedlings, soil for a cactus, jiffys, or maybe rockwool, all this is working fine for seeds.
Even the soil you used and any other pre ferted soil like the normal Foxfarm is useable, but you should flush it with lots of water first, to get rid of the most fert in it...
I recomend you for your next grow to get any good soil it may be Foxfarm or any other good soil, as better the soil, than better for your Plants, but let me tell you hemp grows even in the dirt out of my garden if necesarry.
I'm pretty shure there's not prob at all to use the soil you have for later on at this grow, it was just not good to put in the seeds in any pre fert soil.
Anyway, don't worry about your little plants they may need some time but the still can turn out very nice.
I really thought one of my little skunk#1 is dead, anyway I didn't throw it away, now I call it "JESUS" 'couse its alive again and growing just fine, your little ones look much better than this one in the worst moment...