It's pretty good at European languages, but still terrible at Arabic and Japanese. The system still has a very shallow understanding of the content. One of my primarily Arabic-speaking colleagues was actually offended by Google Translate butchering their language so badly; their culture places a relatively high value on poetry, calligraphy, etc.
As an exercise, try translating your search queries into Arabic before searching. Then, let Google translate the results for you. It is hilarious.
I wonder how much Arabic translation suffers from a lack of available data to feed the ML. [1]
> Nor are foreign books much translated: in the 1,000 years since the reign of the Caliph Mamoun, say the authors, the Arabs have translated as many books as Spain translates in one year.
I am somewhat surprised that our ML is not yet strong enough to make good use of a relatively small, but precisely translated work, such as the Qur'an. The success of human anthropologists in deciphering the Rosetta stone to learn the ancient Egyptian languages must have had as much to do with understanding the context, the culture and tools of the time, as actually cracking a code.
As an exercise, try translating your search queries into Arabic before searching. Then, let Google translate the results for you. It is hilarious.