i bet Luca already made a wish and that had something to do with him returning back in time and that's why he and the other are all slightly different from the novel she read. because this world's time was reversed by Luca at the end of the story and now he prob has memories from his first life and somehow MC got sucked into this story because of whatever Luca wished for...
this is all just my guess and i could be entirely wrong, but it would make sense as to why there are changes from the novel she read and how she managed to transmigrate into this story world...
Great theory!
same
Wonder what Luca will wish for