There's no way to remove a translated image in Content Translation.

I don't remember anybody ever complaining about this, because images from the source text are usually relevant, and the current image adaptation function works fairly well. Nevertheless, I'd expect this to be possible in case somebody does want to remove an image.

The Automatic translation card only handles the caption and not the image itself.

I'd expect this to be doable with another simple "image card" or something along these lines.