Speaking as a Russian, the only real reference to Russian specifically in the books is Vladimir Harkonnen's first name, which was amusing when it first came up, but it doesn't really seem to play any specific role (and ofc his last name is Finnish, so, like most other things in this universe, if it's a cultural reference, it's very syncretic). There is another reference to a broader Slavic culture in one of the Fremen chants in the first book, though:
ima trava okolo
i korenja okolo
This does not directly correspond to any existing Slavic language, but it is very recognizable to most speakers of such - "trava" is grass, "korenja" (pronounced as "korenya") are "roots", and "okolo" literally means "around" (from "kolo", circle), and in some Slavic languages became more generic "nearby". So the snippet should really translate as "grass is around/near, and roots are around/near", but Herbert translates it as "these are the grasses and these are the roots". Then again, many clearly Arabic phrases also have meanings that are similar but not exactly the same as what they really mean, and the book sort of implies that it's just the result of language evolution over time. But it is rather interesting that Fremen of all people apparently have some Slavic language as part of its history. Given that the snippet most closely resembles South Slavic languages, it is likely a reference to Bosniaks specifically, but it's never really elaborated further.
Speaking as a Russian, the only real reference to Russian specifically in the books is Vladimir Harkonnen's first name, which was amusing when it first came up, but it doesn't really seem to play any specific role (and ofc his last name is Finnish, so, like most other things in this universe, if it's a cultural reference, it's very syncretic). There is another reference to a broader Slavic culture in one of the Fremen chants in the first book, though:
This does not directly correspond to any existing Slavic language, but it is very recognizable to most speakers of such - "trava" is grass, "korenja" (pronounced as "korenya") are "roots", and "okolo" literally means "around" (from "kolo", circle), and in some Slavic languages became more generic "nearby". So the snippet should really translate as "grass is around/near, and roots are around/near", but Herbert translates it as "these are the grasses and these are the roots". Then again, many clearly Arabic phrases also have meanings that are similar but not exactly the same as what they really mean, and the book sort of implies that it's just the result of language evolution over time. But it is rather interesting that Fremen of all people apparently have some Slavic language as part of its history. Given that the snippet most closely resembles South Slavic languages, it is likely a reference to Bosniaks specifically, but it's never really elaborated further.