I don't make a big deal about pronunciation.
Especially with words that, in Japan, are meant to be Western, often Anglo-derived to begin with.
I can understand when someone uses a word like "bueno" or "me gusta" or "kawaii" or "neko" in the middle of an English sentence, or similar pidgin. As if English needs to be the language to absorb all other languages in the word. Or even words that have been more widely adopted into English because of their uniqueness or less of a perfect English equivalent, like tsunami, karaoke, or sushi. And people mispronouncing the words terribly(people do that enough to French-English, as it is).
But I don't think that necessarily applies to words that were clearly foreign in Japanese to begin with. And you can be pretty liberal with what you think the original intention of the word is. Sometimes, Japan katakana-izes foreign words very wrong. And I think the best thing to do, is focus on what the original word of the original language was meant to be. For instance, it just seems more natural to say something like Yoko Littner, rather than Yoko Ritona. Though it's somewhat controversial and I don't really care.
Nia is better anyway.