Quote Originally Posted by Kalise View Post
I believe that's attributable to the Echo.

Our Echo allows us to understand all languages (Which is why we can walk into Doma and be able to speak with everyone despite never studying the Doman language)

It's possible that it will also translate other languages into specific accents too.

Kind of like the same reasoning used in Doctor Who with how the TARDIS automatically translates everything into a British accent.
I'm actually fairly certain the Echo isn't involved with translating Doman language; Lyse and Alisaie have no problems speaking to any Othardian people they encounter, and the Echo doesn't impart linguistic translation to nearby companions like the TARDIS. Moreover, Yugiri and Gosetsu similarly have no issues speaking to Eorzeans when they first arrive. I can't check the lorebook right now, but I think all the peoples at least speak 'the Common tongue' (probably not the right term) that's spoken throughout Eorzea and the Garlean Empire, presumably as a trade language and/or because of Garlean occupation.

In regards to the accent, Hien and Gosetsu at least have a slight tonal difference to their speech that suggests an East Asian accent, though I may just be hearing things. They probably didn't bother with outright East Asian accents because it might have come across as silly if they couldn't pull it off, and it's not like everyone sharing the same accent doesn't happen in other media works; I'm pretty sure none of the Japanese voice actors are effecting a British accent, for instance.