I've added the part and its trails mostly using strava heatmap.  I'll leave it up to you to either refine this with additional edits, leave more comments here, or mark this issue as resolved.

Are the feature names on the map marked with signs?  If so, they certainly fall within the OSM map-what-on-the-ground principle and I will look for an appropriate way to tag them.


https://www.openstreetmap.org/relation/18386409