Is there some option to be enabled, than when reviewing words, not only, let’s say, I’d have to translate english -> russian, but also russian -> english?
No but, in some courses, the course creator has repeated and reversed the levels to achieve testing both ways. You can make your own courses that way:
http://feedback.memrise.com/knowledgebase/articles/525137-test-directions-overview
Testing direction is up to the course creator.
Many courses that were designed for testing in one direction, actually work really poorly in the other direction. For example, the course creator may have taken synonyms into consideration only for the testing direction they had in mind, and if it went the other way you’d have ambiguous words where you can’t know what the right answer is. Or they may have written the prompt phrases in such a way that they’re really hard to enter as answers, because you may have to remember the order several arbitrary words go in (if they didn’t use commas, which let you pick just one).
If you want testing in both directions, it’s probably best to look for a course that was designed for it, and has levels that go both ways. For example, my tropical fish identification course ( http://www.memrise.com/course/750078/tropical-coral-reef-fish-identification/ ) is like this - there are levels where you see a picture and type the species name, and other levels with all the same fish where you see a species name and have to choose a picture of it.
It would be really nice if memrise let us search for courses by testing direction! Then you could easily find all the courses in a particular language that have tests going both ways. A bunch of us asked for this on the old forum and the old uservoice feedback site, but Memrise never responded to those requests. So for now, the best thing to do is ask around on the forum for the language or topic you’re interested in, and see who knows of a course that tests in both directions.