What a translation corpus is useful for
Translation software that's any good doesn't provide an out-of-the-spout final version. It provides useful suggestions for words, phrases and sentences, and the translator selects what's appropriate and puts it all into acceptable shape. Translations into English should sound English, etc. Nothing tires or puts a reader off more than non-idiomatic or inconsistent usage. This even goes for stuff that's crap in the original - the translation should read like English crap etc unless you're being paid extra to de-crap it.
That's why this kind of offer is a great step forward. It provides real translators with real suggestions provably used in real cases. Nothing there to stop anyone coming up with anything better.
Out-of-the-spout versions are very hit and miss. The only people who can really make full use of them are those who know the original language and can decipher some of the oddities arising from over-literal translations and misunderstood contexts. More than a page of this for a stranger to the original language is usually mind-numbing enough to bring the reading to a halt, unless you're driven by an extraordinary passion for the topic.
There are a couple of problems with huge corpuses like this, though, that have nothing to do with gobbledegook. The first is the need for constant cultivation - pruning, editing etc, to weed out possible errors and focus on the useful alternatives so that a translator isn't overwhelmed by a deluge of not very useful suggestions. Another is the need to keep terminology precise and up-to-date. A third is more technical - a capability to segment a sentence into useful bits and pieces so that phrases and words are matched rather than just full sentences. Translators who used DejaVu as against Trados translation memory software are constantly thankful for the greater flexibility DV offers in this respect.
Finally, we should be aware of the de-skilling of translation as a profession that is going on. Trados software in particular is time and again used by translation agencies to gouge translators and push rates down. On the other hand, there are still one or two clients around who appreciate that a good translation is worth its weight in gold. They don't want monkey jabber, so they don't pay peanuts. (Note for the business-minded - the time taken to make a crap translation acceptable usually exceeds the time needed to get a good translation in the first place, if the translators know their onions.