I was thinking the same thing.Are you concerned with the inside or outside? If your question is about fit, the shape of the actual carbon on the outside doesn't necessarily mean anything.
You shouldn't require flat shoes to mount Speedplay pedals either in the traditional location or mid foot.I want to fit a Speedplay Cleat in a midfoot position as I tried that position and love it.
Finding shoes that are flat in that area (for me that's about 35mm further back than is regularly possible) is not easy. They need to fit aswell ofc