I remember posting an update on this topic earlier this year but can’t seem to find it anymore, so I’m summarizing the current status here.
Earlier this year, following global community feedback and existing OSM guidance, I moved a set of informal trail names from the name tag to loc_name.
These names originated within a small off-road motorcycle group and, over time, became referenced by others largely because they were visible on the map. Some are clearly informal or humorous (e.g. “Never Again Trail”, “Elephant Poo Trail”). None are signed on the ground or formally documented by a recognized club or authority. Ironically, some of these names appear on local official Thai-language maps despite their informal origin.
Using such names in name=* is problematic because it gives group-specific labels undue authority, reinforces self-referential naming, and weakens verifiability.
Several of these trails have since become restricted to motorized two-wheel access, further arguing against treating these names as authoritative.
As a compromise, I preserved the names in loc_name and shared them separately via a private Gaia GPS map and a GPX download.