VGR fixed a lot of mistakes made in the Black Box, and since it is a constantly changing dreamscape, it's lore is that the lore is constantly changing.
As for the others, they kept changes to an absolute minimum required to support the rules, leaning heavily into creative vaguery. Especially Dragonlance, which, instead of redoing the the original and fixing the vast amount of bad stuff in it, chickened out and went for a side-story, which is pretty pointless when the vast majority of players don't know the main story.