My early Coupelet has the same rounded roof as Centerdoor. But the window is different, i have never changed anything on my car. It was made 22 sep. 1917.
This roof model came soon after the "rounded top",
Which then became the "flated top" with straght edge.
I think that is the first picture I've seen of the half round top trim piece. For whatever reason that piece is rare to find around these parts. I assume they loosened and took flight.