I have a potential way of identifying the Unity NERVE.WAD versions that should avoid false positives:
When scanning a WAD that doesn't match one of the hardcoded NERVE.WAD hashes, check whether the WAD has a DMAPINFO lump as well as MAP01 through MAP09 but not MAP10. If the WAD passes that check, then open DMAPINFO (which has a ZMAPINFO-like structure; see The Doom Wiki for details) and check whether the lump defines an episode called "No Rest for the Living" that starts on MAP01. If so, then the WAD is almost certainly a version of NERVE.WAD, so load it as such.
The lump check should already filter out nearly all WADs, since pretty much the only ones that would pass would be nine-level Doom II WADs made with the Unity port in mind. And I think it's extremely unlikely that anyone today would title a serious WAD the same as an official episode.
(Of course, all this assumes that lumps can actually be opened during the NERVE.WAD check.)