Thanks for taking a look. Some entropy is to be expected. Given the monotonically increasing growth curve, I assume the NYC usage has always been predominant, and the admonition on the wiki was either speculation or a hint to avoid confusion rather than a formal deprecation.
It’s always OK to update the wiki to acknowledge actual usage in the database. A dedicated wiki page about this tag would be a good place to explain the distinction, perhaps citing this discussion.
hgv=local would resolve the earlier concern about hgv=yes being indistinguishable from a default value. I think that’s an elegant solution, though I’m just one mapper. We’ll need to remain vigilant about confused mappers using this tag for other purposes in the future.