I can definitely see why you felt Acceptance explained too much, in retrospect there are definitely a few details in there that could have been left up for the reader to interpret a bit more, although it doesn't bother me much personally. getting the PoV from the lighthouse keeper was indeed a great touch!
I'm a sucker for paranormal investigation type of stuff and Authority really hit the spot for me, replacing the paranormal with the incomprehensible and adding the internal disfunction of the Southern Reach as a nice touch.

Yeah, I've heard so too, I think it's called 'Absolution', looking forward to it, and to reading Borne (whenever I'm through with Cixin Liu's works I've now begun to explore)