>>533457754
>e.g. Grazie having a connection to Tenjian
That one's actually not in the book. Instead there's a modified design with a different comment about the color schemes and how by that point four bosses being foreigners was already decided..
The one with the Tenjian line (here, bottom right paragraph) was posted in an online interview with the character designer.
https://dengekionline.com/articles/155178/
A lot of the things he said there get brought up in the artbook comments too, although there's also a bunch of new points. In the interview he said he thinks Serpentine has the best style, but in the book he says he thinks Serpentine has the biggest chest.