Does NAATI only translate in three directions: English, Chinese and English? Is there an English-Japanese direction?

Level 3 is necessary. Natti has English and Japanese exams, but I don't think it's good for you personally.

Because China students are definitely good at Chinese, followed by English, so China students are basically 100% Chinese and English in natti.

I wonder if your Japanese is better than Chinese. In that case, you can consider choosing Japanese-English translation, because basically all Japanese students will take the Japanese-English translation exam, and whether it is English or Japanese, it will not reduce your difficulty.