I never picked up on any racism inherent in Jynx, but - well, frankly, I'm white, I live in a country where whites are privileged, and it takes a clue-by-four to get me to notice stuff like this anyway. If the writer feels that strongly about it, it's probably worth taking a second look.
If anything, Japan does tend to be pretty insensitive dealing with other races, so it's certainly possible Jynx reflects overt racism on the part of the artist. I'm not sure I agree with her that the name has any significance though.