I just came across this post as I was looking for a recipe for carne salata.
I usually order this dish at a restaurant in Valpolicella and my best guess is that vergelatta has nothing to do with the marbelling of the meat
Typically we are talking about a pretty lean piece of beef that has been cured (salata) not necessarily like salted pork but more like beef cured in a similar fashion to gravelox. I am pretty sure it is typical for the lakes region of northern Italy. Not unlike carpaccio, but sliced slightly thicker it is serverd as an appetizer at room temperture and sometimes dressed with some EVOO.
From my experience with Italian food in Italy as well as my somewhat deterioriating fluency in the Italian language I bet you that vergellata pertains to the slicing of the meat (made to look like paper).
Would be interested in hearing back from somebody.
J