With my serious head on now.
No one in their right mind would argue that being left in a foreign country to look after a sibling isn't a form of neglect and I am sure it is still impacting her. Like you, I have also attended numerous courses on neglect, have numerous books on the subject and might have even delivered some of the courses that you have attended. We have fostered in the past and have seen the impact neglect can have on children first hand and although I have made light of it in this thread, I do fully understand the consequences it can have in future life.
Many other posters have mentioned the lack of food and social interaction with other children as contributions to her mental health, and again I cannot argue against that but, without trying to play down any of it, I do feel that she's sensationalized her story to sell her book - I would like to hear the parents side of the story but maybe they are in on the writing of the book.
This could and should have been an opportunity of a lifetime but was badly planned from the outset by the parents on several fronts and should have ended at the end of Cook's journey but didn't. This part for me is where it all goes wrong and the majority of the child abuse comes in. I would have loved to participate in that first part of her journey but you can see and understand how a dream opportunity could turn sour.
I tend to watch a lot of Ben Fogle's programmes about people living and raising their children in the wild. The majority of these children are well grounded and live an idyllic lifestyle, but I am sure there are many in reality who would love to be running around a tarmac playground playing footy with other kids.
Maybe my view of her adventure lies in the Treasure Island and Swiss Family Robinson books I read as a child.