I don't think transcription from Greek is standardised. I've met several people "officially" called Vassilios or Vassileios or Vasileios or Vasilios while they were in the UK, but they all had the same name (Βασίλειος) in Greek, I think. I don't think the transcription of Russian names has been effectively standardised, either. I think I heard about a recent effort to standardise the Latin transscription of Bulgarian names, but that just suggests that they weren't standardised before then (or were standardised differently, at least).
Also, remember that it's Gorbachev in English, Gorbatchev in French, Gorbatschow in German, and so on, so there isn't likely to be a single Latin transcription unless it's one that's incompatible with existing usage.
Also note that it's usually "Rachmaninoff" in English, because he moved to the USA and became a US citizen at age 69, though you'd normally expect that name to be written as "Rakhmaninov" in English, I think; it's written "Rachmaninow" in German, for example. But that's an example of a different problem, really: people changing their names. While they're alive perhaps you might want to use their current official name, but when they're dead and if they're famous then you probably don't want to be forced to use the name that they adopted as a joke just before they died.
Names are not unique anyway. For most official purposes you should identify people with some kind of number and use the name as a check or to help a human sort things out when something doesn't match and you suspect that the number is wrong.