I hope that Wikiverse projects don't accidentally or intentionally promote unscientific theories, including those regarding race. I would like to think that we know better.
However, there is a history in our world of people experiencing prejudice or being persecuted for race. This is a sad element of history and an ongoing problem in the world. Regrettably, it would be surprising if there were not some problems with these issues in the Wikiverse.
There has been at least one arbitration case on English Wikipedia regarding issues of race, and there have been issues raised on Meta and on this mailing list regarding what sound like well-founded allegations of bias (in more than one form) on a few smaller wikis. I think that one of these cases resulted in at least one local administrator being demoted. I don't have time now to look into the current and historical details of these cases, but I know that they've happened.
I don't know what next steps to recommend, but I think that it's important to acknowledge the issues. I think that the scientific mindset that many Wikimedians have is helpful in limiting bias. In a regrettable circumstance where one or more of our colleagues show signs of racial prejudice, that is an issue that I hope would be addressed, whether through informal conversations (a person may have said something that came across as having a meaning that was different than what they intended), or more formally by local communities or if necessary on Meta. I hope that these incidents are rare, but they do happen.