Somewhat unexpectedly, Koden-KM has updated his old attempt at remaking Ultima 8 in Neverwinter Nights, as he explains in a comment here:

I fixed most of the missed map area links and reset the module starting position back to the Docks. Treasure Cove (Slayer cave) and Stratos areas are the only ones built but not linked. The scripts to get to them don’t seem to work.

I have updated the download available on the project entry here, and you can also grab the updated module from the project’s GitHub repository.