
My guts tell me that Eorzea has one single unified language, with maybe dialects or variations across areas, but nothing that could be clearly identified as different. Pretty much like every spanish speaking country in real life: they all are a variation of a particular language from Spain, castillian. There's actually a crapton of regional languages in Spain, but when you learn 'spanish' you learn castillain, because that's the language that imposed itself thanks to the Reconquest, and so it was the one they used when colonizing America.
So my take on it is that everyone in Eorzea speaks "eorzean" or some kind of variation of it. Not because they were colonized by an external kingdom that imposed something on them (like it was in the case of South America), but because it is stated by lore that all the races have been in the continent for a really long time. So long, in fact, that racial barriers have pretty much fell and dissapeared except on the cases of Ishgard and Gridania who are pretty xenophobic. But otherwise you can find all races all over the continent.
On the other hand, it makes a lot of sense for certain nations (particularly Gridania and Ishgard) to have their own distinct languages. But I'd expect such a thing would have been mentioned by the lore. And that really is the problem: At the end, no matter what our guts tells us, or how logical it'd be to have multiple languages, the fact is that they are never mentioned anywhere in the game except for ancient roegadyn. This pretty much implies that there is only one language in use as far as the canon is concerned.
So my take on it is that everyone in Eorzea speaks "eorzean" or some kind of variation of it. Not because they were colonized by an external kingdom that imposed something on them (like it was in the case of South America), but because it is stated by lore that all the races have been in the continent for a really long time. So long, in fact, that racial barriers have pretty much fell and dissapeared except on the cases of Ishgard and Gridania who are pretty xenophobic. But otherwise you can find all races all over the continent.
On the other hand, it makes a lot of sense for certain nations (particularly Gridania and Ishgard) to have their own distinct languages. But I'd expect such a thing would have been mentioned by the lore. And that really is the problem: At the end, no matter what our guts tells us, or how logical it'd be to have multiple languages, the fact is that they are never mentioned anywhere in the game except for ancient roegadyn. This pretty much implies that there is only one language in use as far as the canon is concerned.