One thing you should know is that in the US, education is not standardized.
If John has a degree, you don't really know what work he did for the degree - you just know that some school was willing to give John a degree. A Doctorate at some schools is 2 years, some is 5 years, some takes closer to 7 - and each department at each schools might have different standards. It probably requires a thesis (but not always). It might require tests (but not always). It might require publishing (but, again, not always). Also, schools can grant whatever degrees they want (it would shock me there wasn't a school somewhere that offered a "Historical Sciences" degree - but who knows what they mean by historical sciences)
So if you're a Candidate in Human Sciences, say that - I agree that you should use cyrillic. And if someone asks what it is, make sure you're clear it's a post graduate degree (based on the description, it sounds vaguely like an interdisciplinary Masters in social sciences or almost an ABD)