Does anyone know how the end of this encounter works? I saved everyone but Matkina later talks about how everyone died. Do i have to have them stand next to the teleporter before leaving? Do i have to not use the tides? does it even matter?

From the description when you activate the teleporter, everyone still alive in Miel Avest should have been teleported out. So, it could just be an error in Matkina's dialogue, like certain characters thinking the second Underbelly murder happened even if you manage to prevent it.

And I don't think it matters, since I know one of the named cast offs died while we were fleeing, and he showed up later.

Good to know, thank you.

From what I could tell, only 2 NPCs actually matter, the 2 named ones that start closest to you. I didn't bother to save them in my playthrough, so I couldn't tell you what effect they might have.
But the generic castoffs don't seem to matter at all, the 2 named NPCs who are fighting at the start probably always survive since you meet them later, and the leader always dies even if she was still alive when you get out.

Glad i took the time to save them then, thanks for the help. Where do i find them later to check?