looked up Leucism on wiki
"Leucism is a condition characterized by reduced pigmentation in animals and humans. Unlike albinism, it is caused by a reduction in all types of skin pigment, not just melanin."
so by that definition, if its truly leucistic, any super lesser combo will be an all white snake, doesn't matter if its a super lesser/super pastel/super cinny/super sable/super enchi/super *insert more morphs here* all in one snake.