So a reference to Ariel is no go because it's Disney, but directly taking Nami as a name from One Piece is okay? Not that it particularly bothers me, but it's just a little confusing how it's fine how direct a name like Nami is while Romnariel is more subtle about it. Don't get me wrong, I'm fine with either, just baffled. More importantly...
What if I told you that Ariel is also a common real world name and NOT invented by Disney?
South Park had it right: you don't **** with The Mouse.
You can generally use the same name for your character as another character in a different property, as long as there aren't a huge abundance of other similarities between them. As long as it isn't Disney. They are entire orders of magnitude more aggressive about the defense of their intellectual property than any other company, mostly because so much of it should be Public Domain and remains under their control only because of their extremely litigious nature.