I 100% think that Luca used the goblet's wish in another timeline, which led to the protagonist becoming Judith. That's why he knows so much, acts different, knew abt the assassination etc.
I read one of the commentor who read the novel, they said yes, luca used the once in a lifetime wish. But don't know what exactly the wish was that makes the times turn back and here he is knowing the plot of his life.
I 100% think that Luca used the goblet's wish in another timeline, which led to the protagonist becoming Judith. That's why he knows so much, acts different, knew abt the assassination etc.