I don't understand you. Considering the quality of your fiction and the covers on your books, I have to guess you have great editors and great designers.
You certainly have great authors. So why do you keep doing this to them?
The main character of this book is described as far-eastern, and dark skinned. She is a "trouser girl" in this alternate Victorian England. Reading the book, I assumed that was a reference to traditional Thai styles of dress.
Here's the cover.
Bloomsbury, something is wrong in your house. Something that makes you think your Caucasian readers (and no argument, they're the majority) wouldn't be interested in reading about anyone of another color. And something that makes you feel it's ok to make your minority readers feel marginalized; to make them feel that whatever they look like, they ought to be white.
Now, I realize that very likely this cover may have been finished and paid for (and a good cover shoot costs a LOT, I sympathize) even before the Liar kerfuffle. Which would mean that it was before you had that shining opportunity to learn something. Which would also mean that you had more than 6 months to fix this.
This writer is talented, and she's innocent. But I don't know how to support her without also supporting you, Bloomsbury. As writers become more aware and wary of you, though, they are going to start realizing that as talented as you are, you're quite a long way from innocent.