Q: Why Vil is so insistent on correcting Epel’s accent?

The short, spoiler-free answer is: the way that Epel is used to speaking back home includes something that is particular to the Japanese language, and it might be impossible to translate into English.

Aniplex USA is doing their best with the localization but a lot is getting lost in translation because the Japanese language and the English language are so very different: Epel’s natural dialect uses forms of speech that are inappropriate to use with teachers and upperclassmen, and that don’t exist in English.

Since everyone back in his village treated him like family (there were no other children his age), he is used to speaking very casually with older people as though they are his equals. Vil cannot have a member of Pomefiore obliviously insulting the students of not only his own dorm but those of other dorms and the school’s faculty.

But Epel isn’t intentionally being rude; it’s just all he knows. So he is rankling at Vil instituting what he sees as frivolous rules, but it is Vil’s responsibility as Epel’s housewarden to guide him in this new territory.

It is not a personal vendetta: it is just Vil doing his job, though neither character is very happy about it.

And there is a possibility for additional misunderstanding on EN in particular, as a line where Vil told Epel that he needs to “speak more politely” was written as “speak properly,” which is a significant change, in context.

This also came up back in 2023, and a user from a Scandinavian country (and Epel’s hometown can come across as fairly Scandinavia-coded, even borrowing words from the Finnish language) mentioned a similar experience in their own life. It is possible that real-world experiences were intentionally integrated into the creation of Epel’s character and his head-butting with Vil.

More here (Tumblr links):
1st: I see some people saying Vil is just correcting Epel because he’s swearing a lot?
2nd: I also recall seeing someone say that apparently Epel speaks Tsugaru dialect in Japanese…
3rd: …Vil trying to teach Epel that it’s not about hiding your dialect/culture, it’s about being considerate to those around you…