The art is magical! But I do agree the dialog is a bit difficult.
However :p yes people do say I'm cumming, and uwaa is a sfx for grunts and other such sounds. And actually an artist is considered a sensei. Manga, traditional painting, photographer, the list goes on. But I think the guy is snapping reference pictures for his ero comic.
So he IS spot on there!
Great job, please draw more!