My thought is: So all of it was fake. Or at least parts of it, like the body switch was just part of her novel.…
from my preference some of things in the novel of her's were true like her acting as his fan and interviewing etc gett meddle in his business and i say the parts where their body aren't switched are real one and the reason real sheng sheng wrotein the book that they switched to body ,to know eo struggles when they broke up and afterwards at the end get together
the present mooyeong didn't went back to future who come to the past just like Lee Yeon he decided to stay at the joseon with hongjoo soo he ain't in the future anymore?? idk I'm confused lol