[Snake]

Or just use the same system of SS13. Whoever played knows what I mean.

If you don't know 'wdf' SS13 has? Here you go:
When you type a certain prefix before whatever, the language swaps around, for example.

Player 1 types:
say "Hi, I'm empire guy."

Player 2's perspective:
Player 1: "Hi, I'm empire guy."
Player 2: "Hi, s'up."

=====================
Player 1 types:
say ";Hi, I'm lupine guy."

Player 2's perspective:
Player 1: "Bow bowowow allah-"
Player 2: "What?"



And for language, each specimen would have their singular language depending where they were born. (I still see this implement as far-off sea stuff, I mean, Onigans doesn't even spawn in their home! Meh.) As for learning, I'm split. People are going to metagame like there's no tomorrow if it becomes easy to obtain the knowledge, or just stuck if it's too hard.
I'd say to make NPC schools for each language, which requires some (or, a lot) of Murai and 'days' to learn?