Hm that's a possibility but I haven't seen any hints on that. I think the storyline changed because of Eudith's treatment to Luka. He may have opened up a little when Eudith tried to be a good aunt to him and when he saw his maternal aunt being so friendly with his paternal uncle (with matching flowers and sparkles as background lol) he must've thought that if he acts mature, cool and adult like he would grab all his aunts attention. Cause yknow they just got close but some stranger claiming to be his uncle was much already close and friendly to his aunt. (Hence the misunderstanding)
To summarize, he wants all his aunts attention? I get that vibe from him since he is a child. Children wants attention.
But there have been plenty of hints. He said "it wasn't like this last time", suddenly knows about noble clothing, suddenly knows how to read, and also how to fight? That sounds like stuff he would have experienced if everything went according to the novel and he time traveled back. Plus he's not reacting like the first time like everything is stuff he's used to (the snow, the train, the clothes) which would all be normal things for him in the first timeline
I think it's just because Eudith sucks at fashion that's why they chose the clothes themselves. That was proven when Eudith tried to pick something for Luka but it was yeah a total fashion cringe (just for comedic purpose of course) And if he really knew how to read then he would've had the confidence to read the book or the daily gossip out loud to prove it to his aunt, instead, he reads it slowly as if he's trying to figure out if the words and pronunciations were correct (you can see the letters on a smaller and different font indicating that he's shy or making his voice small). About the 'fight'.... Well it was hardly a fight at all. If he were reincarnated and had already experienced a battle, don't you think it's a little reckless of him to just suddenly just 'attacked' the assassin with a butter knife? and not thought about the situation since he returned as a ten year old child and already went through the same danger? (Though my reasoning for this one must be too excessive ┐( ∵ )┌).
Please, kid just acted like mature adult and cool Infront of his aunt. He's just copying what he saw in his uncle inorder to impress(?) his aunt. I get that vibe from him.
Like I said, Eudith's change also changes the plotline including Lukas perspective and personality. Remember when Eudith said that Luka in the novel was gentle because he wants to get close or something to the people in the duchy? It's because he was being neglected and was sold by his original 'aunt' that he wanted to be good to his new family. Who knows maybe this grumpy personality was actually his real personality. His first response to Eudith being kind to him was the evidence of my conclusion.
Also, you quoted "he wasn't like this last time" did Luka said that or Eudith? I feel like you're referring to when Eudith saw the thick snow and saw Lukas indifference and compared him to the novel Luka.
If it was Luka then can't you tell me which chapter? I must've missed it.
Chapter 11 page 27 and regarding Luka's reading, he was obviously trying to appear to be sounding the words out. He knows how to read but it would be suspicious if he was fluent so he tried to downplay it. He also reacted before the assassin attacked as if he knew what was going to happen. It's way more likely that he traveled back in time rather than him just "trying to act like an adult". The author made it plenty clear that they were going with the regressor plot
Luka is back in time for sure