In my opinion the master of languages is J.R.R. Tolkien.
What he did with his creation of actual working languages was a miracle.
In my books I don’t have any specific foreign languages that need to be interpreted, but I do have people with accents and unique phraseologies. This distinguishes my characters from each other and gives a sense of who they are.
Another author who used this same concept was J.K. Rowling in her Harry Potter series.
Here are a few lines from her books. See if you can match up the character to their quotes:
1. “Is that my Dudders?”
2. “It does not do to dwell on dreams and forget to live, remember that.”
3. “I say there are spots that don't come off.... Spots that never come off, d'you know what I mean?”
4. No, I think I'll just go down and have some pudding and wait for it all to turn up.... It always does in the end.
5. "He was my mum and dad's best friend. He's a convicted murderer, but he's broken out of wizard prison and he's on the run. He likes to keep in touch with me, though...keep up with news...check if I'm happy..."
6. "Brilliant! It's Potions last thing on Friday! Snape won't have the time to poison us all!"
7. "Yeah, Quirrell was a great teacher. There was just that minor drawback of him having Lord Voldemort sticking out of the back of his head!"
8. “What's comin' will come and we'll meet it when it does.”
9. “The mind is not a book, to be opened at will and examined at leisure. Thoughts are not etched on the inside of skulls, to be perused by an invader. The mind is a complex and many-layered thing.”
10. The ceiling isn’t real. It’s bewitched to look like the night sky. I read about it in Hogwarts, A History
11. "Ah, shut up, Dursley, yeh great prune."
12. "Ah, go boil yer heads, both of yeh,"
13. “Cause I'll look like a bloody idiot, that's why.”
14. “Blimey, Harry. You've slayed dragons. If you can't get a date, who can?”
Aunt Petunia= 1
Albus Dumbledore= 2
Mad-Eye Moody= 3
Luna Lovegood= 4
Harry Potter= 5, 6, 7
Hagrid= 8, 11,12
Severus Snape = 9
Ron= 13, 14