I know a Catholic man from Nigeria who is fluent in Hebrew and many other languages. He is married, had eight children with his Malaysian wife. They live in Britain. So?
So far as White Nationalism solving any kind of moral and spiritual problem, no, it won’t. Have you never read Apocalypse chapter seven! St. John got a glimpse into Heaven. He didn’t mention anything about white nationalism.
The fact is, however, on this earth, most people prefer being around and marrying those of their own race and ethnicity. Most people marry within their own race and culture. Do not fall into the trap of earthly solutions to spiritual problems. Or are you a fan of Francis’ multi-culti nonsense?