I would agree it is copper and not HCl that is the problem, assuming there was copper in there. I used a lot of HCl to clean up a large aquarium a few years ago. No damage to the grass by the driveway. Of course soil conditions, ph, buffering etc are going to vary. I used a few gallons of the HCl fwiw.
If it is copper contamination, there might be some kind of chelating agent (EDTA?) that is safe for the lawn that would help get plants growing back again. Ionic copper (copper sulphate usually) is a really fantastic herbicide.