There is a problem with the font on the Code of Conduct page of ruSO. As you can see below, the font quite different.
As I can see, original font contains Cyrillic symbols. But SO version doesn't, so the browser has to fall back to a local system font for the characters that aren't in the web font.
Could you update the font in CDN, so it looks and feels the same on Eng and Rus pages?
Original question on ruSO: Шрифт на странице норм поведения отличается от оригинального