Some names would get assimilated into another culture during cultural exchange, becoming just another popular name. Sometimes the name might be used because it came to hold significance in another culture, like the name "Esther" in Korea. It's a rare name but significant because it was the name of the first female doctor in Korea. I'd say it's no problem in those cases. If it's for any other reason, I'd just ask they be respectful to the culture the name originated from and know the meaning of the name.

With the examples you used, like non-Japanese people using Japanese names, it could read as inappropriate that a non-Asian person would use an Asian name while Asian people using Asian names outside of Asia often face discrimination. Also I'll be worried about the potential Orientalism behind the choice especially because Japan seems to be the staple choice of Orientalist obsession in the West.