Now that the author no longer has as much control, he can't control Killian as well as before. We already noticed that Killian was being more of a person on his own, struggling with the control that both the author and Reeze has over him (subconsciously, in Reeze's case), but that last bit of info from the system shows that it's not the system that had been giving Killian headaches whenever he wasn't acting according to the plot and instead was liking Edith more and more. It was the author.