As you can see from the question mark, I don't know. So I start using my imagination - in other words: I'm guessing.
Well, "-inka" could be a Slavonic ending indicating a pet form (like in ANNINKA). Which would leave "Zr-" or maybe "Zar-". A Z can always come in for an S in various languages (such as Spanish). So why not
Sarah / Zarah?
I know this quite a vague theory - but this is all I can come up with. So I'm sure, somebody else will have a better idea …