Urgh, this is annoying for them. It would've been much easier for them to use the concept to make an American version, but they're clearly trying to be respectful to the source material whilst still giving the movie a chance to be a global smash.
I hope they explain it in the movie. Perhaps the creator adopted her as a child and wants the best for her that's why he chose a non-asian, and she struggles with the hob because she doesn't fit in etc. I might be more forgiving of the white washing if there's a reason given for it in the story because I understand the business reasons.
We're definitely coming to the end of the era were you could replace a minority with a white person and get away with it though.