As a child, from 2nd to 6th grade, I went to a grade school where the cooks made fresh sticky buns in the school kitchen (everything was made fresh in teh school kitchens and the lunch ladies knew how to make great food.. They were
I've made my own sticky buns, most recently with candycap mushrooms (yeh, I know. That was almost a year ago now, in one of our Golden Chef challenges. Why is it we don't do those anymore?). Like your description, half came out gooey and deliscious; while the other half seemed to develop a crispy coating. Both tasted great though.
I suspect that the sticky buns closest to the oven walls received more infra-red heat, and so cooked the sugar more. I think Convection oven would solve that issue, unless the coating cooked faster than the pastrie, which just might be the case.
In any case, your sticky buns look stunning. They are truly, eye-candy (pun intended).
Seeeeeya; Chief Longwind of the North