Perhaps Harry in book is deliberately dropping misinformation, not unlike the verbal games with Grey in SG, otherwise we have to assume that Jim is being lazy and petulant, not checking his wiki or accepting his beta readers points when they do. I don’t want to believe that.
The three biggies are:-
1. Forgetting Harry had physically been in the BFS before
2. Tunguska and the death of a Dragon
3. The fire in Notre Dame
I think alteration/removal of memory won’t affect 3, it an event that hasn’t happened in Harry time-line yet, as it suggests the fire took place before 2013/14, the other possibility is alteration of the time-line, but Michael and Charity still are married suggesting the last Dragon killed was by Michael and not Eb, ruling out 2. A temporal attack making sure Siriovax was killed at Tunguska meaning no meeting of Charity and Michael to ensure the current Winter Lady was never born would make sense. Conflicting time lines? Harry’s foresight getting confused because there will be an attempt to alter the time -line in the future and he is remembering more than one time-line?
Jim did say he might squeeze another book in the series and mentioned dragons as well to tie up his plot-lines, is it this he is dropping breadcrumbs for? A temporal attack on Harry’s best friend and his family?