Porkie , did the vinegar etch the surface of the coin?
If so you could lightly brush the surface with some scotch brite.
It will smooth out the etching and bring out some of the detail.
I wouldn't do this on a good or valuable coin but seeing the damage has already been done there's nothing to loose trying it.
I etched my Essayons copper button by incorrectly cleaning it and couldn't make out any detail. Doing this brought it back to life but not as nice as it was before cleaning it.
Good luck let me know if it worked if you give it a try.