Currently there are only 2 available roof blocks for wedges (per tier). Ive had cases where im left with bare ceiling as a roof because there are no roof blocks that can cover up a single wedge shape.
Also, when you have a path that is 2 wedges wide ( and lets say 10 wedges long)
It will be very hard to put a roof on it since the current blocks simply wont fit.
Another (more common) scenario could be a wall that is one block wide with a wedge bend in it. For the square foundations you can use the normal rooftop blocks (not the sloped) and the accompanying endpieces however this also leaves the bends bare and roofless.