I don't disagree with anything you said, but I'm afraid you badly misunderstood the comment you replied to.
They aren't complaining about closed captions failing to translate foreign speech.
They're complaining about the specific instance where the show/movie has English subtitles for that foreign speech already built in and showing on the screen, and when the closed captions show "[speaking Japanese]" it overlays the translation that the filmmakers intended the viewers to receive, preventing them from experiencing the filmmaker's artistic choice.
They aren't complaining about closed captions failing to translate foreign speech.
They're complaining about the specific instance where the show/movie has English subtitles for that foreign speech already built in and showing on the screen, and when the closed captions show "[speaking Japanese]" it overlays the translation that the filmmakers intended the viewers to receive, preventing them from experiencing the filmmaker's artistic choice.