So this quest (https://en.uesp.net/wiki/Tamriel_Rebuilt:A_Coldharbour_Keelhaul) got hit quite hard by EoE, but it also had some issues even before the update.

1) During the quest, Devas Terano is supposed to move to the Black Ogre Tavern. The tavern was moved from Bal Oyra to Nivalis, but the script is still trying to move Devas to the old Bal Oyra location.
2) Even if this was fixed, the generic dialogue lines that are supposed to point the player to the tavern were all removed. Also, Devas's accomplice Aligae needs new dialogue lines that would give the player directions to Nivalis.
3) There are also some issues with dialogue filtering. If you finish the quest in the "best way possible" (get Soul Anchor back, don't kill Devas, kill the daedroth), Devas still acts like he sold the Soul Anchor, like he would if you wait three days, and you get an additional gold reward.

There are also two more bugs reported by Cicero (https://www.tamriel-rebuilt.org/bugtracker/soul-anchor-not-spawned-doing...) and Denis (https://www.tamriel-rebuilt.org/bugtracker/tel-ouadas-coldharbour-keelha...), which still apply as well.