Personally I think an even more broad form of the tag should exist (which even could have further justification for its existence). If there was a general word for these shoujo/Isekai/webtoon/drama stories I think that would better encapsulate the real sort of tag that is needed?
You can search by shoujo+Isekai but not all of these stories are actually Isekai and there are a lotttt of stories I would still catagorize as "written for men/general audiences" under the shoujo tag. They're all technically shoujo as well, but I think when people look for a shoujo story they're looking for something fluffy/romantic. Say, something you'd expect out of a shoujo magazine, like you'd expect something action oriented with crude humor from like shonen jump under the shonen tag.
The villainess genre is something I would say has spurned out of a larger new-age shoujo, which I think is of a different genre then standard Japanese flower-coated shoujo manga that a lot of us has grown up with. A saintess tag would be nice but I think a lot of these webtoons and manga could be better united under a tag between shoujo and josei? Unpopular opinion though, probably.