Again, I think you underestimate the organic, human element of electronic music. If it were just machines, people would easily be able to replicate the sounds of whatever they wanted to replicate. It’s a combined element of the tech (and the specific way the inputs are set) and the way it is being played or programmed. I think even if Vangelis wrote down EXACTLY what tech and inputs he used, people wouldn’t be able to replicate the broad, intuitive, almost improvised way he played the synths.
Not that that’s a goal. As I said, I prefer re-recordings that remove themselves much further from the original, to become its own thing. Rothermich tried too hard to be Vangelis, IMO, and didn’t really succeed. The aforementioned Starink did better, hitting that perfect note between original fidelity and something new.