Having read Ray Galea’s book some time ago, it seems to me that he has pure and not malicious intentions. However, it also seems to me Dannii, that most of the research that you are talking about, was done in preparation for the book and not while he was moving towards Protestantism. There is one scene is the book in which he more or less points to his total ignorance of Catholic doctrine as a Catholic. Quite simply, he had received insufficient catechesis as a young Catholic. To a large extent that’s not his fault, but it is deeply telling.
I think that the issue may be one of inadvertent strawman representation than deliberate distortion and misrepresentation at various points. However, I’d suggest that the more significant problems appear to be rather strange leaps of logic in his argument and the non-sequitur nature of some of his observations.
To give you an example of this, in his chapter of Catholicism and the Bible, Galea points to Jesus’ rebuke of the Pharisees traditions, then proceeds to suggest that all tradition is inherently bad, notwithstanding the fact that both Jesus and his apostles repeatedly speak positively about sacred tradition throughout the New Testament. He then makes the observation that because of the role of sacred tradition in the Catholic Church, it is essentially unreformable. Which, if you ask any well-informed Catholic, is precisely the point! Why would you want or need to reform sacred tradition that Jesus had entrusted to his apostles to preserve?
I also suspect that more thorough research would have helped Galea to avoid some of the more glaring errors in his book. For instance, Galea points to the practice of selling indulgences as an example of tradition being faulty. Yet, had he done his homework, he would know that the selling of indulgences was never an authoritative teaching of the Catholic Church and not tradition, as such. He would also have realised that the practice of selling indulgences was outlawed at the Council of Trent. Which, when you remember that Galea points to the unreformable nature of sacred tradition, kind of undermines the idea that the selling of indulgences were sacred tradition in the first place!