A sentence from my current favourite bugbear:
My son's grades are getting better and better. (given translation)
I have two problems with the given translation:
"getting better and better" implies that the grades were good to start with. This translation sounds like the parent is showing off; "My son was already great but now he is even better still". Whereas, I feel that the actual meaning should be more like 'gradually improving' i.e. the grades were previously unacceptable but they are becoming better. What is the actual, natural interpretation of this sentence?
I'm not sure how 段々 and なります interact with each other. To me this seems like it ought to be a future sentence i.e. "My son's grades will gradually become better (but they haven't yet). I want to use なっています、or something involving the auxiliary くる (but I'm never comfortable making my own sentences with くる so I'm not sure about that).
So, is this sentence natural for the meaning given in the English translation? If not, how would you make a Japanese sentence that better matched the English translation?