You are correct. We covered this on the original Long Thread. Frank Marshall Davis' editor explained. The incident referred to a period when FMD was still married to his first wife.
No, the book Sex Rebel Black was published in 1968, eight years after 1960. (And 26 years after 1942.)
1968 - 1960 = 8
The book placed the “Ann” story when Frank’s protaganist was married to his first, black, wife in Georgia; and said “Ann” was a black girl from Jamaica.
I don’t know about Frank’s “editor,” but another son, Mark Davis, who has been trained in disinformation by the military, trolls the Internet and hangs his hat on the Georgia locale to argue Barry isn’t his brother.
But, the preface says “names and identities” were changed (much like Dreams of My Father btw). It is not at all unreasonable to suppose that Anne’s identity was changed, even if her name wasn’t.