I think Vegas are a genuinely good counter-punch team, and have been to varying degrees for a long time, against multiple goalies. However I think you are right that with the possible exception of Vejmelka they've faced no serious quality in net this run. And there is obvious danger in them continuing to play this way. If they keep giving Carolina sustained O-zone time the Canes will punish them eventually, and if a goalie does shut them down enough that the score starts to more consistently reflect the shot count, they're in trouble.
I tipped Vegas in 7 and sticking with it, but if Carolina can keep running them down and putting on the pressure, it could well tell in the end, especially if their PP gets going. I think the Knights have to threaten a bit more beyond just rushes and breaks if they want to take the series. That said, they had a 2-goal lead pretty late here and were well on the way to a big series advantage before they let it slip, and even then I thought Barbashev's stuff-in goal with 5 to go arguably should have counted.
As it is, all square and still all to play for.