Any discrepancies between events in the canon material are just a result of the story being told from two different viewpoints. For example, the last arc of The Clone Wars and the Ahsoka novel do not agree on the conversation Ahsoka had with Maul and the circumstances around their encounter. I believe that the events we see on screen are the correct ones, yet the only reason the novel and the show disagree is that Ahsoka doesn’t remember the events correctly in her telling of the story.
This is also why the Novelizations can sometimes disagree since the story is being told by a different in-universe entity than the movie. A history book can’t be 100% correct all the time. It is not protective to freak out over retcons and contradictions. Instead, gather all the information and decide for yourself whos account of the events was most correct.