I don’t think it’s hard to learn the very basics of any language, but sounding natural and using the most idiomatic expressions is really something else.
As for Google Translate, I read something about it not long ago. Its core has been upgraded and now works as a deep learning AI. Here’s some reading. From what I know, Google Translate is pretty good for some pairs of languages, like French-English.
Like I said, what’s hard is to sound natural in a language you don’t speak at home. Sometimes, when I’m not lazy, I use Reverso and Linguee to find “chunks” of proper English and I plug it here.
