Roughly 50 % of my ancestry is Greek Catholic. This means their church records are mostly written in Russian and/or Slavonic or some variation thereof. They didn't speak Russian though, but Finnish (or Karelian), and the names they used themselves differed from the ones on the records.
The same, of course, applies to the rest of Finland with the church records in Swedish. The Finland Project has a policy that we should use the name in the source.
But how do I do this?
For example, my grandfather, whom I've learned to know as Johannes Repo. In his birth record, he's Іоаннъ Григоріевъ Ребо. His first name could be romanized as Ioann, or ìoann” (ISO-9), or maybe even Yoann or Joann. I don't even know how it's supposed to be pronounced, and it's a very common name. Anyway, it's really just another way to spell Ivan. Which is actually used in some other documents on him, in Finnish too. Ivan was a very common name, and, in many parishes, the name could be spelled Иванъ by one priest and Іоаннъ by another.
Then there’s the patronym. Григоріевъ, or Grigorìev”, Grigoryev etc. Patronyms were only used in church records, though. Can I just skip this one, please?
And then, his last name at birth. It’s spelled Rebo, but Repo was the common spelling and that’s why I’ve used it.
So, which variation of the name should I use? Does it matter where and how I enter the other variations?
(The cyrillic letters broke the styling, sorry about that.)