Feedback about writing a technical book

Early this year I was contacted by Developpez.com to find people to write articles. So I answered to participate on the subject of the Ruby on Rails framework.I was asked to translate part of Abraham Kuri Vargas’s book APIs on Rails Building REST APIs with Rails. This book is a large tutorial of more than 200 pages to build a scalable API with Ruby on Rails following best practices.I thought it could be a good experience so I started.The project was not maintained and the version of the framework studied was obsolete. Examples were therefore no longer valid and had to be repeated. The mess. I tried to contact the author but to no response.So I started to rewriting the book from scratch. As long as I was rewriting, I thought about translate it into Molière’s language.Here is my feedback on the writing of a book of more than 200 pages in English and French.