I asked for Kaname to be on the cover and Kotobukiya selected the rest. Their team also selected all the cosplayers to be in the book and they also chose the illustrator for the official mascot.
As for the cosplayers selected to be in the book, I have only seen a small selection. The Kotobukiya publishing team manage the production. I merely provide Mirai Gaia as a platform to collect CGM data.
From what I have seen however, I saw a wide selection from all over the world. The
Worldwide Cosplayers post has a selection featuring male and female of all shapes n sizes. Not all are exactly Miss or Mr universe but its not about the looks/skill level but more about the passion.