hmm.. I don't agree that Blyton was "bad" as she had affairs (and Roses didn't say that exactly) so wouldn't take "even an interracial one" as implying that interracial affairs were "even worse" - rather than just reflecting how unconventional interracial affairs were at the time.
'Didn't say that exactly' are mealy mouthed words when to quote what Roses said
'Appararently Blyton's personal life was far from good. She is reputed to have had a series of affairs when married'
And then adds
'and even a lesbian relationship. I feel sorry for her children.'
The entire post is about Blyton being 'far from good' and then feeling 'sorry for her children'. And in that context the 'even' portrays the lesbian relationship as worse. Given thT Roses has accepted it's badly phrased, and you've said it may indicative of unconscious bias, not really seeing what you are trying to argue.