I get what you’re saying, IMO “subtitle” should be what is being referred to in the post, a sort of secondary title, whereas the text on screen for translations shouldn’t also be called subtitles, just “captions” is fine, yet they’re commonly called subtitles, who the hell came up with that?
Being an American though, we just call them chips or fries. We may not have much else going for us here, but at the very least we have unambiguous names for our potato snacks.