When doing a total conversion involving Bloodmoon master file data, one of the gameobjects (BM_horker_swim_UNIQUE known as 'The Swimmer' ingame) references a TravelInit script for cell 23,29. At least, I believe those are the cell co-ordinates. It is irrelevant, as regardless of the cell reference, it triggers an error as the cell is no longer listed. Many modders have 'fixed' the problem by navigating to this cell and causing it to initialize in the list of initialized exterior cells. It is actually not necessary to do this, as the problem can be fixed by either deleting this object or removing the Escort script from its AI submenu.

-BioBomber

Is there a TC FAQ out there anywhere? If so, this info would certainly be a valuable addition. Thank you for pointing this out.

There is no TC FAQ because TCs don't run into any problems with this, since they don't use any of BM's data.
However, this creature (IIRC) is a quest thing from one of BM's misc quests. Unless you need that quest in your TC (in which case, it's not a TC), you might as well delete this one.