The person in the question stated clearly that it's a russian-speaking one and asked the whole question in russian. The question was about the old site bug with localized downloads for Tor browser. I have answered in russian - the "edit" completely translated it in english with a machine translation - it's 100% clear that it was not done by hand - it's not correct in tiny language details! Russian answer text was completely removed making it less-understandable to russian-speaking asker. Here is the link https://tor.stackexchange.com/posts/14820/revisions
If you're able to answer in English, then users can always use their own Google/Yandex/etc translator if necessary. The main Stack Exchange Meta has a good explanation of why they require English, which applies pretty well here too.
The editor (canonizing ironize) is not a moderator, but a user who has the edit privilege by virtue of having 2000 reputation. Incidentally, so do you. If you think their edit made the post worse, you can roll it back: the edit dialog gives you that option.
With the exception of localized sites and language-specific sites, Stack Exchange content must be in English. In the original form, both question and answer violated this rule. The question should have been closed as "unclear what you are asking", and deleted together with the answer. Answers in languages other than English are not acceptable.