Are you calculating the offset for the part of the roof that has a different plate height? My guess is the calculation isn't exact, that's why you see a ridge line. I would do two separate roofs and join them. Then, trim out what you don't need where they overlap. I find two separate roof is almost always easier than trying to figure it out with one roof sketch.

As for the valley starting in a different place, that's dictated by the plate heights. The way I'm reading his plan view, here's what I'm seeing (see attachment):
1. The roofs are at the same plate height (by the way the valleys all meet at the corners).
2. But on the bottom right of the roof in plan view, it looks like the main roof rides on top of the front roof.

Something isn't making sense to me. Then again I probably don't have all the info. Just looking at the attachments.