I've heard about cutting those screws to "float" the drywall. That's something we've considered doing for the worst locations.

Thank you for the reply! My understanding is this should/could have been addressed at the construction phase, like you say. My builder is out of the question for any resolution, as they are getting hit with some lawsuits by us and neighbours (surprise, surprise...).

Do you think it would be possible to help address this by getting up into the attic and screwing the trusses down to the top of the wall? I'm unsure, as it all wants to move and will want to continue to do so... it might not appreciate being restrained and that could manifest something worse

The 1/4" gap above our tiled shower wall is a real eyesore that even crown moulding won't fix (shower area = wet)