Lived in cultural experiences is different to "scientific" theories.
Cultural experiences also have historical context. So can be looked at in that way. As well as looked at in current context.
Flat earthers fly in the face of all of that.
If someone is racist. Then deems that material inoffensive but the material is offensive should not have worthy weight. Or weight at all in this. Cultural consultants need to address these. Not just random opinions who did not grow up within the culture.
That's why I pointed out "research". Research is a scientific term. Science is science. Science has the same value regardless of who the scientist is. if the research is solid, the fact the researcher is white, black or whatever MUST not be important.
Now, if you say that a term or behavior is more or less offensive depending on culture or experience, that's an entirely different matter and there can be discussion around it. I remember having the OA books and never giving a thought that they could be racist, even if i admit i haven't read them in a long while.
Full of stereotypes? Sure, but like all role play gaming material. Even the base classes are stereotypes. All cultural representations in all D&D material i have owned is ripe with stereotypes, even "europoid" nations like the Principalities of Glantri in good old D&D Basic supplements.
It does not NEED a warning to tell people that those are the "artist impressions" of the common tropes of Spain, Italy, Germany and all European nations around the Middle-Age/Renaissance. Though a warning does not hurt, either. Surely, removing or censoring is bad.