The door from the main floor of the Zafirbel Bay Company to the Vault is set to be unlocked with the ZBC Dock Key (TR_m2_ITO_HE_KeyZBC02), not the ZBC Vault Key (TR_m2_ITO_HE_KeyZBC04).
There is a wood elf hunter named Ellegrin in the Malacath shrine of Hummurushtapi, in the Armun Ashlands, who is nonhostile despite the other inhabitants being so.
When asked for latest rumors, Nisirel in Tel Gilan says "Nisirel has been spending a lot of time in Drithnil Virith's shop. I wonder what that's all about."
There are a couple of typos and, possibly, stylistic errors in HH dialogue:
Style: "Now some eggs have started to go bad and the whole warehouse reeks of rotten eggs." <-- Maybe replace the first 'some eggs' with 'some of these'. Or, delete the last 'of rotten eggs'
During the second quest in Helnim FG, I went to Ald Mirathi and found Arfil, paralyzed. Then I cleared the ruin (killed everyone except the Bosmer archer on the upper floor) and returned to Arfil. He had 3 sequential forcegreetings with generic dialogue. His unique greeting appeared only after I casted Dispel on him, using the scroll I found in the ruin.