Today I just learned how to switch between languages. You can switch to any language at any time in ArcheAge, however, you won't be able to fully speak it without it getting jumbled up unless you have a sound proficiency in learning the language.
Tip: To learn the Nuian or Haranyan Continent Languages, you must craft or purchase a Tutoring Cushion of your desired language type. You must place the cushion in your home, and summon the tutor. To use them, you must buy or craft an Art of Language book to interact with the NPC. You may do this once every 4 (real life) hours. Each use gives you 1% proficiency.
I wanted to share what I learned so that others can revel in this nifty feature.
To Speak the Nuia Continent Dialect (Shared language between Elves and Nuians): Type /nuia and press enter.
To Speak the Haranya Continent Dialect (Shared language between Harani and Firrans): Type /haranya and press enter.
To Speak the Elven Language (Only Elves naturally speak this. Cannot be learned at this time.): Type /elf and press enter.
To Speak the Nuian Language (Only Nuians naturally speak this. Cannot be learned at this time.): Type /nuian and press enter.
To Speak the Harani Language (Only Harani naturally speak this. Cannot be learned at this time.): Type /harani and press enter.
To Speak the Firran Language (Only Firrans naturally speak this. Cannot be learned at this time.): Type /firran and press enter.
I've currently maxed the proficiency in the opposite faction's language, and let me tell you it is quite the ordeal. You need a tutor, from a cusion you make or buy and place in your house, as well as 100 Art of Language books. Each is consumed per lesson, which gives you 100 proficiency in said language.
You can only study with your tutor once every four hours, and the materials to make the book are relatively easy to farm but end up being rather expensive in both labor cost and/or gold if you do it yourself.
Points to note: The rate of your proficiency works like a chance counter on whether or not a letter in a message is translated when it appears on your character's chatbox. In short, 20% (2000) efficiency would result in a message with ~20% of the letters translated. K*#d o& (#k! *(&). (Kind of like this.)
This works both ways. If you're semi-proficient in the language and try to shout in it, others of the opposite faction will catch some of your letters. Though once you reach max proficiency, in-game limitations means it becomes hard to tell if it's a red or green that's shouting the message, unless you personally know who it is or try to send them a tell.
It does appear to be an actual algorithm, but I can't puzzle it out. The scrambling effect is determined by the case of the letters in the word, and the entire composition of the whole string. So for instance, if you first type: "hi im looking for some rp" then type "Hi, I'm looking for some RP," they'll be completely different.
One other thing to note is that at 100% proficiency, you are also only really at 99%, and a stray scramble might appear in your words. You're still understandable, it's just a little annoying.