On this question asking about contact tracing in South Korea a user wrote an answer to the question in Korean (now undeleted): https://politics.stackexchange.com/a/52880/19301
In the comments, another user translated it using google translate, and it appears to be an accurate and useful answer to the question, though it's lacking sources. Shortly after this, though, the answer was deleted.
What should have happened here? On StackOverflow, I know that the the rule is that questions and answers should not be translated, both since a translator might make a mistake, and because if the OP cannot speak English, they won't be able to answer important follow-up questions or confirm that the answer is correct. Do we/should we have a similar rule here? In this case, the translated answer seemed like a good one which completely answered the original question, but the language barrier would likely have gotten in the way of getting sources for it.