I think it's important to take into account the true size of each city-state. Even though there may only be 150 or so visible NPC's running about, that doesn't mean there are only 150 citizens of the city-state. SE can only program so many NPC's into the game after all. There are in fact probably hundreds of thousands, if not millions of citizens in terms of real lore. As such, it's perfectly believable that different cultures exist within each city-state.
That said, there technically is no such thing as "German," "Spanish," "Japanese," or even "English" languages in this world. The primary language (English in this case), would probably be considered simply "Eorzean." But it's perfectly reasonable to have different variations of the language. Just look at American English and British English for instance. There are some words that mean entirely different things. So someone using "goldpaw" instead of "seeker of the sun" wouldn't be too contradictory to lore in my opinion. As for other completely different languages, they could always just be considered tribes of some sort.
That said, there technically is no such thing as "German," "Spanish," "Japanese," or even "English" languages in this world. The primary language (English in this case), would probably be considered simply "Eorzean." But it's perfectly reasonable to have different variations of the language. Just look at American English and British English for instance. There are some words that mean entirely different things. So someone using "goldpaw" instead of "seeker of the sun" wouldn't be too contradictory to lore in my opinion. As for other completely different languages, they could always just be considered tribes of some sort.
