I broadly agree with the OP.
I think MM did receive racist treatment.
I don't think MM was ever welcomed warmly into the RF and accepted in the same way as KM.
I don't think MM's family were offered appropriate support and contact from the RF and their staff in the run up to the wedding. They were left floundering at the centre of a media circus and, being dysfunctional, toxic and desperate for the limelight, this led to a lot of the drama that turned the press and public off H&M.
I think MM expected marrying H would be like a Disney movie with endless ball gowns, premiers, meeting exciting people, travelling the globe and living a life of luxury. Whilst some of that is true, I think she was woefully underprepared for the reality of life as a senior working royal and the intense schedule and lack of freedom that entails.
I believe that both H & M have nasty tempers and I believe the claims of mistreatment from their staff.
I believe that W & K are similarly cut throat characters.
I believe that Charles has prioritised his relationship with Camilla over the wellbeing of his sons and that this has had a more profound impact on H than his brother.
I think H is very unwell and desperately unhappy. I think he is traumatised over the way he lost his mother and I think he resents Camilla and his father. I think this (and the fact he's not very smart) has caused him to cling to M and to fall for the manipulation tactics of Opera and her team.
I think his behaviour is coming from a place of deep hurt and that he is being encouraged and used by people around him for their financial gain. I don't think his primary aim is to make money or to damage the RF; I think he feels hurt and exasperated and is lashing out.
I think H is unprepared for the predictable backlash from this book.
I think the marriage will end in divorce and M will do the media rounds with Opera and the like, spilling the details of their private life.