Wait though.
And I admit upfront I’ve not read either book, but I don’t think you should find it devastating that stuff an author never intended to publish, that was written before the “canonical” work (TKAM) contradicts the work.
It’s entirely possible that as she thought about the characters, she decided to send them in a different direction from what she showed in earlier, unpublished works. And that may even be the reason she never published GSAW, because the characters were in fact different people.
It’s like complaining that a first draft has differences from the published story, except that its the author’s conception of the character that has evolved, not the plot line. (Please don’t confuse this with a character changing over time in the published work, that is ordinary character development. This is the author recasting the character entirely.)