well aware of it Jim, if it was one of mine or any of the clans that were on more than long enough to refresh their claims, it would not be an issue. Since it is not, their structure on the area is an issue and is blocking game content.
I wish I could help since I feel your pain. Unfortunately, the officials would probably not intervene since the spawn is not in a direct line to end game or an exploit. I searched for a while where @Ignasi published the ruleset and couldn’t find it.
Having said that, there are two things you can do and I would recommend the first:
Get the clan or character name from the door of the structure and periodically check for them being online, then talk to them, politely asking them to move the building while letting them know what they are missing. They want that spawn, too ! You might consider offering incentives in the form of raw mats to rebuild.
Plead your case to Ignasis in the form of a DM. The first one is highly recommended before doing that.
Once they move, place a sign or three there that says “Please don’t build here it blocks a valuable spawn.” You may also want to mention the spawn; they probably don’t even know about it.
Best of luck, and regards
Edited PS: The link you want to read carefully is: