No they aren’t. White women having been doing it for years but in line with commentary on racism and class, long colourful nails tend to be labelled “ghetto” on black women” and “chav” on white women.
Also there is no “black community”. Black Americans had a lot to say about Adele’s bantu knots and Jamaican flag bikini. Black Jamaicans did not care.
As for braids, the types that tend to get labelled “cultural appropriation” by some people tend to not be the braid styles worn by the European groups you mention.
But the gatekeeping tends to go both ways. Black people who do Irish dancing or ballet tend to get a lot of vitriol on their social media from some white people.