That was just an example, the Russian magazine isn't the only source talking about the language in question. I mentioned it because he complained about that source and then just started ignoring it when people translated the thing.

Of course. Being written in another language doesn't affect notability; it just means in practice, foreign sources aren't as desirable as native ones. (They are harder to find, harder to understand, harder for other editors to verify, etc., and naturally you will see less of them at any time.)