there's no "someone else got it"; it's always there. Just go back and forth with the lit lamp in hand and eventually it will become visible. You may have to go outside the normal lit range and back in to get it to show.
The Lost Lands book had the same issue of disappearing and reappearing.
As for the Shard/facet mix-up, do the average non-omniscient character in the game (NPCs) really know the difference? For example, without context, does a typical Pacific Islander not in the Marianas, Guam or Hawaii (where they are likely to have US history & geography classes) know the difference between Georgia the US state & Georgia the nation?
Truthfully, considering just HOW different the other facets are from Tram/Fel, Ricardo brings up an interesting potential blockbuster. What IF Trammel wasn't originally a facet, but ANOTHER (NPC-only) SHARD, that the magic of the Crystal of Duplicity ALTERED INTO A FACET - and what happened to the original occupants? And, if so, what evils would those who did it unwittingly be responsible for, if Trammel was born by effectively overwriting another Felucca-only shard? After all, the crystal was Minax's, and she was hardly all sweetness & light.
Don't be so quick to dismiss what might seem as an obvious error. There could be much more sinister truths yet revealed. And, frankly, the tpye of incident would fall in quite well with Ultima (non-UO) lore, and explain in-game why Lord British chose exile, rather than resuming the throne, because in gathering the shards of the gem of immortality, he found out the horrible truth of what he'd done in creating Trammel. And, that itself, might explain why the TB faction will disintegrate in the new system, once they realize what LB & his mages really did...