I have been pleased to see that the entries I am reading have all chosen to build upon or add to canon in interesting ways, but I think simplifying the theme of the contest as "canon changing" would not quite be accurate.
Having had much enjoyment in developing and editing Chronicler stories for Anthology 2 and 3, I found that the stories I enjoyed most took little breadcrumbs from Paizo products that hadn't been developed yet and created their own explanation as to how a mystery occurred, etc. As a writer and GM, I have found it incredibly fun to be able to "play in Paizo's sandbox" and take a kernel of an idea from an NPC stat block or one or two lines in the Inner Sea World Guide and run with it. I believe that is what this contest theme hoped to encourage. I don't think the goal of the contest, nor the Chronicler itself, has ever been to cut huge swathes through existing material and re-write it willy-nilly.
We admire and respect the Paizo crew too much.