Well, ZUN says she's a type of amanojaku in her music comments, saying there's 2 of them now...
In that case, there's a contradiction, because her profile says this: "This power is similar to that of amanojaku, but she is a divine spirit ranked far above amanojaku."
Seeing how all lunarians are big-shots and supposedly the gods they refers to, Sagume might very well be the original "amanojaku god", the one Seija's youkai species is based on, so it isn't really an error to call both of them amanojaku. Besides, there's the problems of having to deal with translations, not the original text. A simple mistranslated term, or even just a bad/different choice of words, can change how something is perceived. In this case, "she's ranked far above amanojaku" could probably become "she's a top-class amanojaku" or something similar if another translator wanted to use that wording. A stupid example: in the wiki and even in the english patch of EoSD, Rumia's english title in the scenarios was written as "the youkai of darkness" until not long ago, despite it being "the youkai of the dusk".
GRINTongue that brings misfortune, my ass.
I'll reverse back anything you made as many times as it takes!!No need to keep your mouth shut...!
Just talk however you like whenever you want to!!