You seem to have a pretty good handle on English. Congrats on that. I think Google is choking on the word "contrivance." To my ear, the word contrivance means "something that was created." So a test is something that was created to see how the student. . . " I think that part of the problem that google is having is that the word "contrived" means "artificial," or "not natural" in some cases. But, I don't think the word is meant to have a negative connotation in this sentence. It just means that Exams are made or designed to see how students solve problems. I hope that helps!

Also, keep in mind that the receiving country calls the person an "immigrant" but the country who gives the person away would call this person an "emigree."

Wow. This is a difficult question to answer. The "in" is definitely needed. But how can I explain it? I guess the "in" is necessary because it shows "when." You could also say, "During what may be a first. . . " That phrase is very common in journalism. Like: "In what may be a first-of-its-kind competition, contestants were challenged to give up their phone for a year." "In what may be the president's last address to Congress, he said blah, blah, blah." "In what may be the most anticipated movie of the year, Kevin Bacon plays a retired police officer with a checkered past. " it is also common to say "in what might have been" as in: "In what might have been the greatest fight of the century, Mohamad Ali . . . " But I don't think you've correctly understood the "has astronomers on the hunt." They are not forced to hunt. Instead, they were excited to search for crater because that is the natural desire of astronomers: they want to discover new things.

I would learn a single phrase and repeat it a lot. I would also try to people's names as close as I could to how native speakers would say it. For example there is a world of difference between Patty (Enlish) and Pati (Spanish). 

"Luther argued that everyone should be able to read the Bible in their own language.". "I think that you could strengthen your argument by citing a few examples where increasing taxes led to more innovation and job growth." so, Argument is not always the same as "fight," especially in the context of political or academic debate. But, it is not the same constructive criticism.