If you're really comfortable in Russian, you might want to try the LBook firmware. The Hanlin V5 is branded as PocketPro in the US and LBook in Russia (same device, different brand name). I've never tried it with a Russian book, but would assume that since it's written by Russians for Russians it should work.
I would recommend FB2 or ePub as formats. Word and RTF files never worked well on mine. If you use Calibre, converting into these formats is quick and painless.
After writing this, I noticed that you were looking for help with the 6" instead of the 5".
I don't have any experience with any of the firmware options for the 6", but LBook has firmware for it.