I think my original thought was maybe that he wrote it with August’s help… but now that I’m reading some of the theories on the Blue Fairy I could see that as an option as well.
I’m not so sure about Regina writing it, interesting as it is. She didn’t know who August was… or the story of how Emma broke away from the curse, right?! Then again, August added his story to the book… which again, makes me wonder if the Blue Fairy had written it, why wasn’t Pinocchio’s story included? Is it because they weren’t supposed to know he took the second spot in the Enchanted Tree? That can’t be the only reason… whereas if August was somehow connected I could see why maybe he omitted his story until absolutely necessary.