For the West:
The quest markers remain over the Barrels even after we've grabbed a backpack of Spare Parts, rather than moving to the available Broken Ballista to prompt us to repair one:

(It would be easier for people to know what to do if the markers updated from Barrel to Broken Ballista to Repaired Ballista / Barrels again, always indicating available Repaired Ballista as well as either Barrels of Spare Parts or Broken Ballista depending on whether we're carrying Spare Parts at the time or not.)

The first Barrier, where Azah is met, does not have a progress bar:


There's a pylon near Skordo's platform which cannot be targeted except at the very base or very top, the crosshair will simply jump and cannot be aligned over most of it. I think it's the one diagonally opposite the pylon which is out of sight and has to be targeted from a different platform/angle, I'll recheck my recording and confirm.

For the East:
His frost breath will sometimes cut straight through the shield, or at least its animation looks to be, and something will kill me when that happens, so it probably is him.

For the Titan:
I had the barrels despawn as I approached them on one attempt - didn't reoccur, but it was every barrel I ran towards, until the fight reset.
He's resetting if we drop to only one person alive, it doesn't even take a full wipe to have to start over, is this intentional?