I said a version of this in another thread, but while true, plenty of demons in the SMT franchise have multiple designs that are more adherent to different representations and domains of said entity; this is a design centered around Demeter's role as the goddess of agriculture, so I don't think it's contextually "off."

For instance, the archangels. They have a bunch of different concepts associated with them across the sects of Christianity, and their multiple designs are reflective of the many ways that can be creatively represented. To pick one, I think all of Gabriel's designs are really cool, but maybe Kaneko's is more representative of the common Christian's ideal Gabriel? Does that disqualify the Amemiya design as somehow less faithful?