I don't know about the reasoning, but it gave "evidence" for its observations in much the same way a human composer might. In terms of "understanding", it seemed in the ballpark of what I get when I ask it to explain some code.
I don't want to paste in the whole giant thing, but if you're curious: [0]
[0] https://drive.google.com/file/d/1D5yICywmkp24YajboKHdYFcBej0...