It sounds like a very interesting book! Which means you accomplished goal one of most book reviews: catching my interest and making me consider reading it.

I think you've already highlighted your biggest issues: few followers, added to a pub after self publishing, book reviews having a limited audience.

I think your title and opening could be stronger. I've never heard of this book so I wouldn't have clicked on your title. Once I started reading the opening didn't make much sense to me because I had absolutely no clue what the book was about.

For a book review or discussion to do well on Medium it needs to target those who've already read the book and want to discuss it or think about it more and those who don't know it yet. The trick is to capture both audiences.

Write your opening sentences with the assumption the reader doesn't have a clue about the author or the book. That doesn't mean start with a plot synopsis but at least give some context.