Tsubaki's hair really isn't sort of possible, it's like taking a marker to hair, what's going on with Saya is still largely unknown, Nu being artificially created isn't much of an excuse with Noel and Lambda being blondes. As for Platinum, yes, her hair has three tones, blond, orange, and pinkish/peach, it gives off the general appearance of a blond, but it is still a very unnatural shift.