He probably did overlook that detail. I read an interview where kubo pretty much said he doesn't think about the location of hollow holes on characters that don't have them already exposed. Later he gave the location of some previously unknown holes in the Unmasked Character Book but the list only included the espada members.
Coyote Starrk: (胸部) chest/ pecho. - Baraggan Louisenbairn: (胸中央) center chest/ centro del pecho. - Tier Harribel: (下腹部-子宫) lower abdomen-uterus/ parte inferior del abdomen-útero. - Ulquiorra Cifer: (胸部) chest/ pecho. - Nnoitra Gilga: (眼部) eye/ ojo. - Grimmjow Jaegerjaquez: (腹部) abdomen/ abdomen. - Zommari Reroux: (右乳首) right nipple/ pezón derecho. - Szayel Apporo Grantz: (亀頭) glans penis/ glande del pene. - Aaroniero Arruruerie: (左大腿部) left thigh/ muslo izquierdo. - Yammy Llargo: (胸部) chest/ pecho.