To say that fiction is inaccurate is kind of nonsensical. I mean I get it, there is representation of a real culture. But at the same time, any fiction book is an alternate reality anyway. I haven't read this book but I suspect any inaccuracies have minimal (if any) impact on the story being told.

As far as advances and who gets them, I think that's a matter of what the publisher thinks will sell. Publishing is a business after all. These days it is almost trivial to self publish so everybody absolutely has the opportunity to tell their story. Getting someone to buy your story is another matter entirely. I'm not really sure how under-representation is being measured. Under represented in terms of advances from publishers?

Also, Wikipedia states that the author is of Puerto Rican and Irish descent. Doesn't that maker her Hispanic? I mean it would if she were running for president...