I don't know how well black americans accept mulattos or "light skins" as they call it.
from a distance as a non-black person, I can make out that black men put mulattas on a pedestal. which is essentially their idea of what a pretty black girl looks like.
from what I can tell blacks fully accept mulattos into their black community by the fact that they still call them niggas. steph curry for example is a mulatto or light skin. but I can tell that he is smarter, calmer, and more white whereas his darker black teammates are more aggressive and chimp out more.
mulattos however are not accepted whatsoever by whites. even liberal whites.
as for the asian community, some of us accept hapas but some of us don't. oh you're half white? I'm gonna be less friendly to you, less likely to invite you to get togethers, etc... obviously not all asians are this way but some of us will micro-aggress/shun those hapas.
whites from what I can tell fully shun hapas. whites are brutal to hapas and mulattos.
either way if I come across a mulatto or hapa I always try to gauge their mental health. usually I can detect some mental fuckery in them (it takes one mentally fucked person to know one).