Bozjan lore is properly scuffed.

[Iscah]

For the Misija part, it's because she's Bozjan. The Hrothgar we meet are all Bozjans and Bozja itself uses Slavic naming conventions. For example, Misija literally means Mission. It's the same thing that you can see with Domans and Hinganashi Hyur using Raen names.

That's the thing though - it's not all races of Bozjans using those names. One of the group of three Resistance fighters mocking her early in the storyline is a Roegadyn with a Roegadyn name, and the Bozjan Hyurs like Aggie and Isolde are using Midlander names. So at very least there's some confusion there.