Ship-generated crewmembers who have Nepleslian (English) names are usually following a theme. On the Sakura, there was Cherry, Blueberry, Sunflower, etc. Those themes are determined by the plotship's GM.
Fay's sprite "evolving" into a free Nekovalkyrja is a good path for players of other Nepleslian-named crewmembers to take, but isn't strictly expected.
For Yamataians and Nepleslians (and the rare Geshrin), there can be rational reasons why a character might have a Nepleslian given name or surname, yet also have a Yamataian (Japanese) name. It's not even been five years since
Nepleslia seceded, so the mixing of the two "races" pre-secession reasonably creates circumstances that could lead to the name difference (a traditionally Yamataian family mixing with a traditionally Nepleslian family, for instance).
"Natural" (factory-created) Nekovalkyrja, unless there's a compelling reason otherwise, have Yamataian names. A Nekovalkyrja mother would likely name her youngling something Yamataian (even if it has a Nepleslian root).
Fred's suggestion is best — the name can mean something in Nepleslian, but should still be Yamataian.