Over the year Google Translate has really improved their online translation. One thing Google has going for them is that they allow people to help the AI learn by adding the correct translations to the system. This alone will correct some of the errors in translation and help translator get simple sentences correct or almost correct.
Understanding French and English I have seen that some words in English that can be used in a sentence in different ways will not always be translated correctly.
The word back is a good example.
I'll be back.
Come back soon.
My back is really hurting.
In French, there are two different meanings for the word back and in translations, I've seen them mixed up so much of the time. But overall Google has one of the better systems to do translations that will help you understand what a person is saying. Nothing is perfect and especially when it is done by a machine.