I’m learning German, and I quite often use this test. Google Translate fails this most of the times. This is true even between Hungarian and English. The difference with the latter one is, that I can properly choose between the options given to me, if there are, without translating it back. Especially, that that passed many times when it gave terrible translations.

So this test fails many times, and even when not, the translation is still usually not good. However, when you don’t care about nuances, it’s still fine usually. And also translation seems to be better if the text is larger. Translating a single word does almost always fail. Translating a whole article is usually fine. But even there it matters what you translate. Translating the Austrian subreddit fails quite often. Sometimes completely for whole large posts. Translating news is better.

Round tripping is definitely better than nothing, but it lets through a lot of "engrish" errors with multi-meaning words and with implied perspectives. Cape as in clothing and cape as in pointy seasides, general as in military rank vs general as in generic, etc.

e.g. "Set up database as: [read replica]" and "Database setup complete: [a replica was loaded.]" may translate into a same string in some language.