I am using google.maps.places.Autocomplete object and always get results in Ukrainian language.
I am loading library like that
http://maps.google.com/maps/api/js?s
Have you tried language=ru instead of language=ru-RU? This works for me. For example, you can input address to Autocomplete in any supportable language, but autocomplete.getPlace() will return result in language from parameter and in case of Russian only ru works.
Have a look also at table of languages: https://developers.google.com/maps/faq#languagesupport
There is no ru-RU, only ru.