What if Byakuran’s hair is actually orange?
Byakuran means dandelion. Dandelions are yellow/orange. Then white.
Conclusion: Byakuran’s hair matches his flame colour, but he dyes it white.
I just had an epiphany
EDIT: Thanks to the person who pointed out that Byakuran meant ‘’white orchid’’! I am an idiot who remembered ‘’white flower’’ and confused it with his dandelion-like hair *laughs*