I noticed you made some tweaks to this script following this bug report: https://www.tamriel-rebuilt.org/bugtracker/coldharbour-keelhaul-will-not.... However, if following Noga-Togroi's instructions and keeping the spear (he says Molag Bal lets you do that after all), the player still gets teleported to Baelkashpitu after three days, and you get a journal entry that you have failed. This happens despite the quest being marked as finished, so something is obviously wrong with the script.

There is also an error in the journal, saying that Devas Terano has taken the silt strider to Bal Oyra (journal index 50). However, there is no silt strider connection to Bal Oyra, so this should be fixed.