I use Google Translate extensively to help write things in Japanese - considered (one of) the most difficult languages in the world.

I show the results to Japanese people who nearly always tell me it looks just fine to them.

I have also passed off translations as my own work on tutoring sites like Lang8 and had natives correct "my work". They often will give a slightly different wording, but I have never had an "WTF does this mean?" type response.

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I think it is important to distinguish the difference between a perfect translation with nuance, and a simple "I need to make this point" translation that is what we need most of the time.