Check each one of those mods' respective pages over at Nexus (or wherever you downloaded them) and see if they mention anything about the town hall specifically. To start your investigation I would recommend that you simply make 100% sure that you don't have a single mod that modifies anything to the Nipton Town Hall to start with. It depends on the types of mods you have as well of course. at some point or another you just won't be able to load your game anyway since it relies on data coming from mods that just won't be there anymore (which won't even be related to your original issue).
Additionally, if you save the game with dozens of mods installed, and then remove a number of them. a lot) at figuring out what's causing the problem, lest you remove mods one by one and try your saved game again every time. Maybe it's just related to data not loading properly there following a fast travel (regardless of mods). I doubt that there would simply be completely missing meshes in the default non-modded game, but nothing is impossible when it comes to Bethesda game bugs. Seems like a mods compatibility issue, either conflicting with another mod that makes changes in that specific interior map, or simply conflicting (glitching) the default game assets of that location.
