Imagesets go under "Imageset", not "Artist CG". Get this shit off of my frontpage
That might've been a bit unhelpful of me. The "Artist CG" category is for (generally) commercial Pixiv and DLSite uploads that don't qualify under any of the other categories. Somebody's trying to class this gallery as Western, but going by the contents of the images alone, number 37 at least is probably made by a Japanese person. In any case, there is no "Western Imageset" category.