Japanese is really difficult to translate. There's so much unstated context, totally different sentence structure, concepts that don't exist in English. I use Google Translate a lot with Japanese, but more to check my work. I'm not sure it could even really work with this kind of interface (sentence a in -> sentence b out).

Check out jisho.org- it will translate and call out sentence structure, and is clearer about assumptions.

I almost wish Google Translate provided a confidence measure.