Why isn't there a word tab in Russian yet?
are you sure you did everything correctly? I just tried it and it works fine
1) open the main page in a language that has a word tab
2) open a discussion page (so you have 2 pages open now)
3) in the first page switch the language to Russian
4) in the second page click on words
if the page reloads when you click on words then it will give you error 404