Something that always bugged me about how most fantasy universes are put together is that problems with language aren’t nearly as widespread as they should be. Usually, there’s some sort of common speech or standard language that covers not just the area where the story takes place, but sometimes the whole world.
A Song of Ice and Fire isn’t as bad in that respect as Wheel of Time, where even the Seanchan across the sea speak the same language as everyone else, but the former only really has accents that don’t vary noticeably from North of the Wall all the way to Dorne. You have to go to Essos or the far north to hear anything different, unless you happen to know a Dothraki or someone from Asshai. Sure, the Targaryens are involved in this happening but languages are hard to kill and therefore it should be expected that more would remain of the original linguistic diversity in the Seven Kingdoms than just accents.
As much as fantasy readers love to give Tolkien grief for cliches they claim he started, it seems to me that the problem lies with his imitators rather than with him. Take the Silmarillion for example (which I often do because it’s the best). Though he doesn’t present much untranslated Elvish speech, he spends what others might consider too much time describing how the Moriquendi (Elves who stayed in Middle Earth) and Calaquendi (Elves who went to Valinor) language families diverged, how names in both differ, how politics affected what languages could be spoken in which kingdoms, etc. His whole universe was built around these constructed languages, primarily as an exercise in tying language to mythology, or more accurately asserting that the two are one and the same. This is sort of glossed over in the trilogy, especially the movies, but I guess that’s to be expected.
The universe of The Default King, at least the first two volumes, is based primarily on Renaissance Europe. This is when print media began to change the way states used language as an aspect of national identity. Sure, Latin had been the language of government, religion and law up to that point, but with earlier publications like Dante Alighieri’s Divine Comedy in Tuscan Italian and Luther’s Bible printed in the High German of Wittenberg, some regional dialects and languages were preferred in official and popular media over others. This was particularly the case in German, where Luther’s Hoch Deutsch later became the basis for Standard German used today. That’s not to say that these regional variations don’t still exist today, only that they often compete for official recognition alongside standard versions of the same language.
This is what happens in The Default King. While Matthieu and others in Heilicon speak their own dialect of what’s referred to generally as Ossiric, there are differences between this and the speech of the royal court. A proclamation read aloud (of necessity, because literacy was restricted to those of means, such as nobles and merchants like Matthieu’s family) in the courtly speech would sound flowery, probably a bit antiquated, and the listener would have to compensate for differences in pronunciation. Some might not understand more than a few words strung together, coming away with the opposite message of what was intended. Naturally, this causes problems.
Moving farther from Heilicon, a traveler would encounter other languages that blend in some regions but remain relatively unchanged in others. This is often a result of trade or relative location to cultural centers. Eventually, you’d get so far out that your own speech and that of a common person on the street would be mutually unintelligible. Depending on the paradigm they subscribe to, anthropologists refer to these centers as the “core” and outlying areas as the “periphery”. I’m a big fan of this idea and it plays an important role in how language is used in the story. On top of this, you also have mixed languages like pidgins and creoles that develop when vocabulary (sometimes grammar) is adopted into an existing language to facilitate economic and/or cultural exchange.
An example of the former appears in Volume 2, when Matthieu meets a merchant from the Arcino Confederacy (the Ossiric League’s nearest western neighbor) and speaks the courtly language of Vauish with him, while the merchant responds in his own dialect called Kicheri. Examples of the former will show up in a few more volumes.
I guess I could sum this all up by just saying that world-building is only as complex as you want it to be, but I appreciate complexity when it’s presented in a logical fashion.