If noting else, this claim served to highlight the difference between UK & EU libel law. It's no surprise Amaral's books about Madeleine's case have never been published in the UK as the onus would have been on him to a actually prove his (libellous) claims were not falsehoods. No "proven facts" were ever proven in a criminal court.
Perhaps that's why some of us have such a hard time accepting that ECHR decided his right to free speech prevailed yet the McCanns, due to judicial secrecy laws, were denied the right to publicly defend themselves against all sorts of allegations from PJ sources prior to the book being published. The McCanns became public figures with their freedom of speech curtailed so the balance of human rights was already weighed against them.
Did his book damage the search? Maybe...in the eyes of the public rather than the authorities.
Did his book harm the McCanns' reputation? Probably not as much as the harm he'd already caused to both them and Madeleine during the investigation.
Ultimately, Madeleine's case has been kept in the public eye over the years by this prolonged lawsuit. Some of us hope that the result will come back to hit Portugal where it hurts.
All IMO.