A translation that only flips the margins has not been edited. Arabic has its own measure, its own weight of a headline, its own way of holding a qualification before the verb arrives. The English page can put the news in the first six words. The Arabic page often has to earn the right to be that blunt. We edit for that, or we do not call it a translation.
When two pages are the same piece, they share a slug and a language link, and the page says so to search engines in hreflang. When they are not the same piece, we do not invent the missing one. The language switch then opens the section, not a phantom article. The untranslated piece says it is untranslated. That sentence is part of the editing.
Machine output is a draft at most, and not one we will sign. A proper name is checked. A number is checked against the same source as the English, not against the English sentence. If the source was ambiguous, both languages stay ambiguous.