Certain trail names have been in use within outdoor communities for an extended period and were subsequently added to OpenStreetMap using the name tag.
Additionally, some mappers have introduced their own custom names, such as Nat’s line, Peter’s Path, Tech trail, Never again trail, among others.
Since none of these trails are officially signed or documented, and the names are in English rather than the local language (Thai), the current use of the name tag is incorrect. Therefore, a cleanup is needed.
Furthermore, some of these “names” are activity-specific. For example, while Never Again Trail may be challenging on a dirt bike, it may not be as difficult on foot.
What is the recommended method for tagging these names?
Firsts check if the object should be realy in OSM. Then loc_name or nickname are options but the name should be in use by more than a closed group of people.
If there is no sign the route relation usually should not be in OSM at all. If there is other rvidence for the name but no sign then it should be “name:signed=no” (or similar, for other tag).
When the people that put the name on the trail also are the ones that use the trail most often, then I’d say, they can name their trail at wish. I observe such trails here sometimes, unofficial even illegal MTB downhill trails. The downhillers are the single users and spend quite some efforts on those trails. Are yours of that kind?
If on the other hand, the trail has lots of other users, then I’d consider that wrong. No idea though how to tag such intricacies: mtb_name:en perhaps? (That might even apply to the other kind just as well.)
I think if there is a commonly used name that’s OK even if it’s not signed and unofficial. In your case these might just be made up by 1 person, so it’s dubious. If you’re local to those trails & think that’s the case then deleting is probably OK. Changing it to one of your suggestions like alt_name:en, or alt_name:en is OK. I like nickname but I don’t think it’s used very much.
I’ve run across something similar where folks have added names to unpaved roads near me. I decided to just leave them since I don’t really know if it’s a commonly used name or not and in my case they made sense since it was associated with some geographic feature