Is it possible that in the kitchen, the new wall framing that extends to the roof is acting as the necessary roof/ridge support in place of the missing ceiling joists? I can see where they doubled up the outside joists, and did a good job in boxing out the new opening, but I don't see any other significant framing in the area.
I also seem to recall that throughout the length of the attic, there are additional framing members attached to the roof rafters (not all rafters, maybe every 2nd or 3rd rafter), running parallel to the ceiling joists, about halfway up (I have bumped my head on these SEVERAL times!) as well as vertical members from the attic 'floor' to the same rafters. If you were to apply wallboard, you would end up with a small square 'tunnel' or hallway directly under the ridge for the length of the house.
Don't worry, I will still hire an engineer, I am just curious about the workings of the house. Also, I figured I should have a basic understanding so that I understand the engineer and any potential contractors that I may hire.