As a practical matter no African-American wants to purchase a home in KJ, and as a realistic matter none have ever tried, because they’d feel completely out of place where virtually 100% of the population is Satmar Chasidic Jewish and they’d be the only person out of tens of thousands of people who are not. So none have tried.
The homes in KJ are privately owned and can be sold by the private homeowner to whomever they want. So any issues on this regard would simply be a matter between the private owner of 429 Torah Avenue (or whatever the address of the home in question) and would not be a public municipal or governmental matter.