I think it needs to be removed from the official map, it's completely overgrown and abandoned past a certain point.

If you mean the part that hugs the west side of Allamuchy Pond, I walked that too. I only added to OSM that part that was easy to follow because the trail starts fading out the further south you go until it just disappears.

Yes, I only add trails that I have walked myself. I'm not sure what particular segment you're referring to, but if it's the Allamuchy Pond Trail that leaves Allamuchy Road south of the pond, I did walk that and it was very well maintained.