YGO Omega supports all officially supported languages. Because Russian is not an official language, it is not, and will not (unless it becomes one) be supported. We have tried to have fan support languages, but between the nuance of the languages, inconsistent support, it is incredibly difficult to maintain those languages. Yugioh has thousands of cards and tens of cards coming out every month. The requirement for people to maintain those cards, accurately, is a lot to ask for, even more when they are doing it for free.
For this reason, we cannot take up the challenge of supporting Russian.