Legit, I'm starting to think the Japanese side calls her Hijiri just 'cause it's more convenient to pronounce. Like, the same case with calling Minamitsu "Murasa".
Wait a minute, "Hijiri" literally means monk. It's not her family name, but her title? Like, "Hijiri Byakuren" is basically "Sister Byakuren"? So a similar idea to calling Miko "Taishi"?