I also have the problem. Emailed supportdos2@larian.com with my save file, hopefully they can fix it for good. Anum Quoi, that is very good that you went to all that trouble to reproduce the problem - and that is not related to any one mod.
Edit: Here is the reply I just got from Larian:
Thank you. There was a hotfix for this issue after patch 6 was released. It has come up again due to a change in patch 7 combined with mods that affect story. Unfortunately, disabling the mods after this occurs will not help. This should be fixed in the next update, but there is no ETA for when that will be.
You should be able to teleport past the shriekers, and/or use sneak or invisibility (sneak or hold Left Shift to display their sight ranges, and where they can detect sneaking characters). The easiest workaround (depending on what you did earlier in the game) would probably be to free Slane, the Winter Dragon, so he will show up to kill them for you.
Raze
Edit #2: I replied to Raze with this question:
Thank you Raze for the swift reply. Slane came to the rescue. Question: If I disable mods before moving to Act Two and then reenable them once I am in Driftwood, does that circumvent the problem until the patch comes out?
He replied: Unfortunately, it is any loading that triggers the problem, not just on act transition.
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So yeah, just gotta workaround the problem, it seems. At least Larian knows about it.
