The big difference between meat that we humans eat & feeders for our snakes is that we cook our food & that kills bacteria, whereas our snakes eat raw food.
I wish I could guarantee that your feeders are safe, but I don't think anyone can do that...I think it's LIKELY that they are OK, especially since they were not
deliberately thawed (ie. they remained in their packages and weren't handled) so they had no additional outside exposure, only the bacteria they "came with".
That's a huge loss to toss, and if you took a poll here, I have a feeling that most would try refreezing & feeding them. And I'm basically against re-freezing &
re-offering, but in your case, I think you're right "on the line" & probably OK...again, with no guarantee. Crossing my fingers for you!
BUT- when you go to deliberately thaw & feed these, pay close attention...sniff for "off smells" (discard if they smell funky) & listen if your snakes say "no thanks".