Unofficial Skyrim Special Edition Patch

I'm not entirely sure this is a bug, maybe Lost Valkygg is the exterior and the interior is just Valkygg?

There are 3 records with the name imprinted on them:

1. The map marker outside. "Lost Valkygg".
2. The worldspace entry for LabyrinthianWorld: "Lost Valkygg"
3. The Location record: "Valkygg"

It's not clear when or if the game would show you what the worldspace record calls it, but that's 2 records vs 1. Usually that's enough to decide it, but it's 50/50 if all you have is the map marker and the location record.

Not that this helps in making a decision in this case, but the local map isn't all that the location record text affects. It didn't occur to me at the time I made this report that the location record determines how the dungeon name is displayed in the journal for a radiant quest. For example (as it is now) the journal will say something like: "Kill the leader of Valkygg" or "Retrieve <item name> from Valkygg" and so on.

Pretty sure you're right about the worldspace entry never showing up in the game. All five of the walled cities in the game have their own worldspaces, for example, and I think (other than the map marker) the location record is always what determines how the name is displayed.

The only reason I brought this up to begin with was because it was an inconsistency. Cases like this that are 50/50 are next to impossible to make a good decision on unless there's some other reference to the location's name like a book, item, or NPC dialogue. There aren't any such references in the game from everything I can tell.

Would it make any difference if the Prima Official Game Guide lists the location's name as Lost Valkygg? I don't know if that's considered an official source for in-game information or not.

Personally I'd call it good enough to use as a tie breaker.