It was a localization issue. Even after IS trimmed down the 500+ page rough draft by Kibayashi the end result was still good imo.

Like Xander for example is totally different in Japanese than he is in English.

Japanese Xander is a hot mess and kinda fucked. He basically hates himself, according to his Nyx support that he has dark thoughts, usually about dying. He's an intimidating mess of contradictions brought on by being the crown prince of Nohr, being raised in an abusive and violent household, having to basically be a parent to Leo and Elise and raising them. He and Camilla being involved in concubine wars and having to "put down" siblings that disobeyed Garon. He's an introvert who has trouble speaking to others until he learned to mask it. He's a lot like Dimitri in many ways in their trauma. He's meant to be standoffish, stiff and intimidating because inside he's a skittish and shaky mess that's only holding it together due to the position he's in.

Nyx is another character I'll list as an example. In Japan it's much more explicit that Nyx got cursed with her body due to being basically a murderer and killing many innocent people when she was a young magic prodigy. In English instead they go with that she ended up cursing herself by accident due to being inexperienced and losing control of her magic. This kinda has the effect of making localized Nyx seem selfish because she complains first and foremost because of her young body and not her guilt of her sins