(Not directed at you specifically)
Is the reviewer truly aware of a string of DNFs and a NM? (I'm not sure if adding more NM actually does anything) I've asked my reveiwer(s) but I know the answer as to how they handle these. To paraphrase - We address each issue as needed
Is there some sort of statute I can follow so I know when it's time to escalate? You'd think after a year of problems I could request action without being the bad guy.
There is no set process for reviewer action regarding strings of DNFs or long-standing NM. As a player, two consecutive DNFs or a NM log is enough for me to filter out a cache using GSAK and avoid looking for it, especially when I'm traveling. As a reviewer, I give cachers a lot more time before I start nudging them (see above).
I review caches for Alaska which has a fairly small number of caches (~4300), so with five PQs I can pull every cache in the state, crunch them through GSAK, I create a list of caches with four or more consecutive DNFs or a NM attribute. For the caches with serial DNFs, I'll post a Reviewer Note suggesting that the cache owner check on their cache and let the caching community know via a Note log that the cache is all right and just tough to find, replace the cache, or archive it themselves, knowing that eventually a frustrated cacher will drop a Needs Archived (NA) log on the cache and "force" me to "officially" look at the cache and potentially take action. Once an NA is written to a cache page, I'll archive fairly quickly if the cache owner has not logged onto the site within the past three months or so. All of my archive notes include content informing the cache owner then can have their cache unarchived within thirty days if the contact me, but prior to unarchiving, the cache will receive the same review as a new cache.
NM attributes by themselves won't prompt me to archive a cache, but I will drop a friendly reminder note on each cache page displaying that attribute in the Fall suggesting that the cache owner take care of any issues before the snow flies and maintenance will be more difficult. In late Spring as the last of the snow melts at lower elevations, I'll drop a similar reminder note on each cache page suggesting that the cache owner may wish to spiff up their cache before the summer caching crush begins. The notes have tips on how to clear the attribute if maintenance was performed and the cache owner didn't clear the attribute with an Owner Maintenance log.
No, there isn't a specific guideline on this. However, I don't see anyone being the "bad guy" reporting issues of any sort about a cache if there is a problem (lots of consecutive DNFs, bad coordinates, private property, soaked log). The only "bad" guys and gals I see out there are the cache owners who take issue with chachers for bringing issues up or don't respond to NM and other logs with at least a simple "I checked on the cache and it's where it's supposed to be" note to the cache page. Even if one doesn't watch the cache logs stream into their inbox, it's very simple to check all of one's caches online through one's profile by looking for the NM attribute and then go check or fix the caches with potential issues.
Your volunteer reviewer experience will vary depending on work load, total number of caches in the reviewer's area, etc.