Google knows it is translated. I think Google, in backend, translates all the articles written in top 10 major languages and then keep them in its directory. Why will Google do that? To fight spam, plagiarism and translated content.
I think Google has an in hour plagiarism checker which is way more stronger than any other company in the world. Google just simply do not give its access to users.
I think Google also has system where its bots automatically rewrites the content and matches it with other contents to check if somebody has done it to fool Google.
In backend, Google is way bigger company than we think. Google may have system for each and everything.
Why not? they have money. they can develop anything. They don't bother if it cost $1B or $10B. They have system to make this much money in less than a month. Simply disable AdSense, charge advertisers more than normal and nobody will even notice it.