Nahhh.. I think Elin wrote that book. She's sketchy and creepy af. She just confused why some people are not wagging their tails for her like how it was "supposed" to be. Maybe she's a witch or she simply knew the "future".. maybe that's her divine ability or something..
Naah, SPOILER ALERT!! (〜￣△￣)〜
some transmigrator is in Elin's body and they read the book, hence why she knows the plot, also i think she evil, but they they took her out of Elin's body and the og Elin is very nice and not sus lol. But this is base on the spoiler i read, so not really sure if it's true
Honestly my theory for the next chapters would be that Elin also got the prophecy book just like Phil, and is trying to make it come true but since Phil knows what to do to change it, it makes Elin's life more harder and now she's trying to make the emperor like her just like in the book...