Sensitive archaeological sites such as Indigenous Australian rock carvings.
Recently, an Aboriginal Rock Carving site was approved close to where I play. The actual submission was for a small silver sign just on the boundary of the site which reads:
“Aboriginal Rock Carvings are an integral part of Aboriginal culture. Please help us preserve this site and the engravings here. Do not interfere with the rock surface in any way.”
In terms of criteria, these locations are obviously a slam dunk:
Historical and cultural significance?
Massive on both fronts.
Amazing works of art.
Varies, but generally okay.
Where things become problematic, though, is that there are typically two extremes of these locations.
One extreme includes locations that are set up for tourism/visitors with installed boardwalks, fences, educational signs and other features that would generally make these locations local tourism attractions. In my opinion, these are not an issue as Wayspots and if anything make high value candidates.
The other extreme is more complicated.
There are many hundreds of thousands of Aboriginal carving sites scattered across Australia, with varying levels of access. Many of these occur away from formal trails in state and national parks.
A good number of these sites are intentionally left off public maps unless expressed permission is given by local elders (someone who has been recognition as a custodian of local cultural/spiritual knowledge and lore, who has permission to disclose it.)
For context, the Australian OpenStreetMap tagging guidelines state:
Please practice extreme care when mapping sites (such as rock art, middens, fish traps, streams, birthing trees, sacred areas and other historical /ceremonial places) that are known to be of significance to Aboriginal and Torres Strait Islander peoples. Only map these sites when they are sign-posted or have been publicly advertised. When they have not, please consult with the local elders before mapping any such site, and abide by their wishes if they say they don't want them mapped.
Other mapping companies have similar policies, but they aren't as accessible online.
The case that I mentioned in my first paragraph is certainly not advertised, nor is it marked with a trail marker "Aboriginal art site this way ⇒".
The signage that is present means something more along the lines of "there's some really sensitive, irreplaceable ≈5,000+ year old sacred carvings sitting exposed on the soft sandstone right in front of you, don't drive or walk on it please" rather than an invitation for people to frequent the location.
While I won't pretend to speak for Indigenous groups, depending on the location in Australia, some of these sacred sites also still play an active role in various cultural ceremony and traditions, and it may not be especially appropriate for these locations to become POIs in a game/AR database for that reason.
Is there any guidelines to cover situations like this?
In terms of Wayfarer, there are currently no such rules excluding these sorts of places from nomination or from acceptance. And in general, neither the nominators nor the voters can be expected to know about the conservation rules, unless listed explicitly on the signs.
If you have a way to contact the custodians, they have the authority to ask Niantic to remove any involved wayspots as they appear. But yes, doing so after-the-fact can be problematic.