A Ring of Endless Light had telepathic or, at least, telepathic-adjacent dolphins, but you're not wrong about the rest of the Austin branch, as far as I recall. I remember Troubling A Star mostly for its jarring callback to prior in-universe events; apparently El Zarco was deposed in a bloody coup, to which I said both oh no! and *ex*cuse me! :( Way to undo everything Charles Wallace and company did. Yeesh.

There was at least one novel involving Meg and Calvin's daughter Polly that *did* deal with time travel, forward and back, and people previously encountered only in might-have-beens. That one I enjoyed, for the most part. It's been ages; I should reread.