I recently got to talk to a very good fan-translator, who ended up doing a few pieces of professional work for AnimEigo. Many people, don't realize that superb English ability is necessary to do a good translation. What you are doing is understanding the nuance and possible artistry in Japanese, and then rendering it in English. For example, a fifth year Italian student could probably read and understand Dante's Inferno. But more likely than not, he couldn't translate it very well.
Culture is another issue in translation.
Different vocabulary, different etiquette, different ritualized phrases, and different values are all very important. Quick Japanese lesson, for those of you not familiar with honorifics in the example. Ranma is just a name I'm using. Actually, there are several subtle connotations in each of these suffices. For example, if you meet someone for the first time who is your superior, using -san might actually be considered inappropriate.