The main plot from the books aren't canon to the games since it's a separate continuity, but some elements of them are, like the personality of characters or the date of an event that parallels the games. Even Scott intended it to be that way.
"The games and the books should be considered to be separate continuities, even if they do share many familiar elements." - Scott Cawthon, December 18, 2015
A very good example of this is that William Afton's name was also revealed through the Silver Eyes. It was still canon before it was used in the games. Besides, the games have never said that Henry /didn't/ wear Fredbear, so it's not a retcon or going against the canon. It's simply something that we can assume is true.
Hope this helps!