A lot of people, including those who aren't translators, will say (repeatedly) that good translation is about much more than replacing words with words. As a translator myself, I would say that this is probably at its most apparent with commonly used words and their different ranges of meanings and uses between separate languages.

A long time ago I did a project which was a large legal document from German to English, where I kept seeing "vorgesehen", which would probably make many native speakers of English think of the English word "see", at least as a starting point ("pre-seen", "foreseen", or "something like that"). But when you enter this word on Google Translate - and we all know that machine translation software is notorious for being unreliable, through no fault of its creators - it translates it into English as "provided" or "scheduled".

That's the correct sense. But even then, legal document writers can be particularly prescriptive and rigid about the terminology used in what they write. Chances are they won't accept wording that is "good enough" even if they will openly concede that it is accurate. This source http://www.dict.cc/deutsch-englisch/vorgesehen.html shows how awkward it can get. "Im Vortrag vorgesehen" can mean "intended by the contract" or, as the source shows, it can mean "provided in the contract" or "required by the contract". But this means that, in a sense, "vorgesehen" can mean "provided" or it can mean "required", which is pretty much what you'd call opposite in meaning!