Frankly, I have to respectfully disagree with you Flynn/Eugene’s character in the game was vastly different compared to his role in the original movie. Basically as the Stabbington Brothers were written out of the game and replaced with Marluxia (believe me EVERYONE but their Grandmothers saw this a mile away when the film was announced as a world and knew he was going to replace the brothers when they saw the Reaper Nobodies) he is the ONLY thief that steals the crown and his reasonings on why he wanted to return the crown and Satchel in KH3 felt not only lacking and “forced” but it had little to no purpose compared to why he wanted to return it in the original movie.Hmm, that is a bad plot hole, but I think the crown one is worse. At least with Flynn, we can assume he is having a moment of weakness in considering whether to steal the crown.
Hans might be the worst of them all. He never has a line, is never given a name, and is never addressed in the plot other than that one instance when Sora remarks that someone is carrying Elsa away.
I'd say the worst one was when Sora, Donald, Goofy (who is supposed to be the intelligent one of the trio) didn’t grow suspicious with Mother Gothel after their first and ONLY encounter with her especially when she coldly dismissed them and said they were “useless and of no help”. I mean If I was present with them and after our first encounter with Gothel once she dismiss us and leaves, I too would be the first to question and feel suspicious about Gothel especially when she coldly dismiss us as “useless” and wether if she really is Rapunzel’s “real mother” (which she isn’t). Even if they didn't know about Hans or physically met him back in Arendelle at least they know he's up to no good compared to their only encounter Gothel who they remained blissfully clueless until Marluxia tolds the trio through Context.
Oh yeah and Marluxia, I'm sorry but even if Marluxia thematically fit the world, neither Rapunzel and Mother Gothel respectively never brought up his name again for the remainder of the world after their first and encounter of him which made his appearance very pointless in the world. At least with Monstropolis, Toy Box and San Fransokyo, the inhabitants do acknowledged the Organization XIII member (Young Xehanort, Vanitas, and Dark Riku) and not brush them off like it never happened compared to Kingdom of Corona, particularly the former world when Randall had a "teamup" with Vanitas.
I'm not saying Arendelle is above Corona or better than that Corona, that's not the point, but when compared to the other KH3 Disney worlds stories I feel that Kingdom of Corona was below The Caribbean, San Fransokyo, Olympus, Monstropolis, and Toy Box.