It’s not about being a linguistic nerd. I’m a linguistic nerd, too. I could talk for hours about how interesting it is that Cent and Hundred are actually cognates, and how in languages descended from Proto-Indo-European, some languages that have a “k” sound instead have an “h” sound in their cognates (“Cynic” and “Hound” are also cognates). Or how about half of the English vocabulary come ultimately from Latin, because William the Bastard conquered England in 1066 and the language of the elite slowly changed the language of the common people. That is all fascinating to me. But I also don’t think it has much applicability at the table. There are bits and pieces you could include to make the world feel more alive. Like maybe there’s a country where the common people are humans but the elite are elves, so people use a lot more elvish words. That could be an interesting bit of worldbuilding. But I think regional languages, especially ones accurate to the Middle Ages where communication is much more difficult than it is in the modern world, would not a fun game make.