The biggest thing is that learning another language isn't a process of translating. There are many words that cannot be even properly translated. My Japanese is pretty terrible. But by watching tons of anime I've picked up many things that I find to be pretty intuitive but feel unable to translate to another language.

Eg: Kawai or Moe doesn't really mean cute.
Otaku isn't some word for nerd.
Kami is a word used for God but omnipotence isn't taken seriously within the Japanese culture (although they love the Bible...... but kind of like the way people love Lord of the Rings)

And I'm just coming from the anime sub-culture.