When they say that common doman-hyur's tongue stands out as slightly odd dialect, I can't help but think of the difference between the Scandinavian languages - Norwegian, Danish and Swedish. Danes like to refer to Norwegian as "Danish with spelling errors" and with both languages it is generally possible to have a conversation, even though we're all only versed in our own languages. So what you might come across is a bunch of words that you understand but have a dialect (The swedish likes to say Danish sounds like we're trying to speak with a potato in our mouth) to them, mixed with words that have been adapted into their own thing.Â
Personally I think if we assume that if the standard eorzean/hyur tongue is English then going full on doman-is-japaneese is taking it too far, rather I would see it more as the bulk of it is understandable both ways, but with some words that have evolved into being their own thing - which may then need some additional explaining or translating. And then I would probably also guestimate that their spelling deviates most of all, since even in Eorzea illiteracy is (supposedly) a common problem and there have been mentions of big changes to the given grammatical rules per region because there's no real unified consensus on how to apply grammatical rules.
Personally I think if we assume that if the standard eorzean/hyur tongue is English then going full on doman-is-japaneese is taking it too far, rather I would see it more as the bulk of it is understandable both ways, but with some words that have evolved into being their own thing - which may then need some additional explaining or translating. And then I would probably also guestimate that their spelling deviates most of all, since even in Eorzea illiteracy is (supposedly) a common problem and there have been mentions of big changes to the given grammatical rules per region because there's no real unified consensus on how to apply grammatical rules.