Really to step beyond the story, in order to explain your ability to understand all characters and not have any linguistics quests in the game, the developers of the original 1.0 version of the game decided to give you an ability called the echo. Part of the Echo is to allow you to understand all languages. I believe Minfillia mentions this in the 2.0 story. If you go read the thread "The True Nature of the Echo" many of your questions about this will be explained.