Probably this current question has the same root problem as another of my recent reports Already translated strings have lost their translations. However, now the affected strings in Transifex have already been translated (some even a couple years ago), but are not being used on the site. E.g. on ruSO:
For instance "Closing" was translated 3 years ago and previously was used on the site.
Is there some issue on the Transifex side?
It would be good if someone can confirm if the same behaviour is happening on other localized sites like SO on Portuguese, Spanish or Japanese. I don't have enough reputation to test closing question on these sites. Probably the other strings might be affected.