If you click on Speakpigeon's name on each of his posts, you get a grey box that says that he's a male in Paris, France, EU. So I'm guessing that English might be (or may be) a second language for him. (If so, he was taught well. His English is very good.) But maybe he was taught the might/may distinction in a way that sounds peculiar and a bit off to native English-speakers' ears. It may (or might) be a bit disconcerting for him to learn that native Anglophones of the Californian (me) and Australian (you) variety don't use these words in quite the way he could have (eek!) conceivably learned was correct. I'm inclined to think that regardless of the subtleties of English usage and when it might sound better to the ear to use one or the other, 'may', 'might', 'could be' and 'could have' can all be symbolized in formal logic by the modal possibility operator.