I've had the same issue sometimes even when US is set as both region and prefered language. It might have to do with the fact that the search "C#" is also found on the Russian page version. When I search C# in general the first answer I get is the Russian version of the wikipedia page.
Might have to do with "Partnership with Yandex." It is a Russian Internet Company.
posted by floey 3 years and 10 months ago Link