Words aren't enough to convey a message and at many points the message is lost if you simply translate literally everything. Not only that, much repetition is created. Japanese are more forgiving with word repetition than westerns, they tend to reuse the same phrases over and over without much any problem.
But when you are translating you must find synonyms and be sure it fits your character.
For instance a very common phrase "Jya, ikouze!" which literally means "Well then, let's go!" needs to be changed once in a while to "let's keep moving forward" or "let's proceed".
On the other hand we have terms in Japanese that just don't work in English. So this is where the biggest headache comes: What works, and what doesnt.
See you later guys!