Just found a post where another user makes a valid point.
comment #8350092
Incubus, incubi, and succubi all get replaced when used as a tag with demon
Succubus however has its own tag and does not imply demon.
Incubus and succubus are subsets of a type of demon, male and female versions respectively. They should not be replaced with the generic demon species tag but instead add the demon tag as a secondary when tagging them.