I'm curious what the domain is and what languages you're talking about, it's hard for me to evaluate your claims otherwise. I would buy it for English -> Tibetan for instance.
My observation of the failure rate (if you define failure as "meaning has been lost") is well above 80% with Google Translate for these languages and this type of text.
It's literally unusable because you have no confidence that the translation has not completely reversed or garbled the meaning of the text, and the failure mode is particularly unpleasant because you may be unaware that it has failed to translate correctly, since it produces text that appears to have meaning - just the wrong meaning.
Your comment about Chinese feeling like English written in Kanji is really interesting to me, perhaps it's a case of different perspectives - I tend to focus on grammar when learning a language, and so Chinese feels very different to English from my perspective.
But Asian languages are nevertheless related in more mysterious ways. Compare the intro to https://en.wikipedia.org/wiki/Mainland_Southeast_Asia_lingui... :
> The Mainland Southeast Asia linguistic area is a sprachbund including languages of the Sino-Tibetan, Hmong–Mien (or Miao–Yao), Kra–Dai, Austronesian and Austroasiatic families spoken in an area stretching from Thailand to China. Neighbouring languages across these families, though presumed unrelated, often have similar typological features, which are believed to have spread by diffusion.
In a European context, this is similar to the unusual closeness between the "unrelated" English and French, known to be due to intensive contact between the languages post-William-the-Conqueror. (In a world context, English and French are closely related regardless.)
It's not "literally unusable." Even for language pairs with poor translation, it considerably saves on manual translation time if you can have a translator look over sets of already translated (but lower-quality) sentences and correct those with errors.
Plus, there are actual studies out there comparing human translations to machine translations in a double-blinded evaluation by translators and the gap is not as high as your comment suggests.
For chinese-english (the other direction), bilingual evaluators have had difficulty differentiating between the machine translation and the human translation.
Having attempted to use CN->EN machine translation many times, I find this very surprising. Have you got a reference I can have a look at?