As a Japanese person, I don't think Google translate can always translate English sentences  into Japanese sentences correctly. In fact, it often makes up wrong sentences in some ways.

If you would like to translate only very simple sentences such as "Hello" or "Do you speak English?" into Japanese, Google translate will help you greatly. But when you translate a little bit complicated sentences, it often tells strange sentences.

For example,  an English sentence "I'm afraid it doesn't make sense to you" was translated into a Japanese sentence "それはあなたには意味がありません" by Google translate. But this Japanese sentence means "It is meaningless for you." or "It is not sigificant for you." They are different from the original English sentence. I omitted "that" between "afraid" and "it" in the sentence on purpose, then Google translate failed to interperet it.

So I don't think it is a good idea that you use Google translate when you translate long or complicated sentences into another language or when you want to say something in another language exactly.

I'm sorry I don't know any practical machine translators, because it is very hard to develop machine translarors for general purpose, so typical free machine translators can work well only if you use them for translating simple sentences or something in a specific field.