Our daughter's oranda was clearly having swim bladder trouble, so we applied the recommended salt treatment. Two hours later, both fish seem dead!
I've tried resuscitation, pumping fresh water through the gills, and even aspirin. Nothing. Are they really gone?

What kind of salt was used and how much? If it was just sodium chloride (NaCl) and nothing else, then up to about 2 tablespoons per gallon even would not kill the goldfish. I suspect either too much was added, or it was not pure NaCl containing some other chemicals perhaps.

I've not heard of using aspirin to revive fish. If the fish do not respond to touch and their gills show no signs of movement, remove them from the water. If the fish still don't move, they are most likely dead. I've had pond fish who appeared dead but in fact made minute movements that told me they were still alive. But at that point, it's usually too late anyway. I'm so sorry that the fish died.