I just approved an edit to the inequation tag. I approved this edit so that the current state of the tag would have some fixed point of reference for discussion. That being said, I do not believe that this tag should exist.
Tags should help to classify and categorify information on MESE so that it can be more easily found, and so that users can filter posts on the site to fit their preferences and interests. In this framework, I honestly cannot see a use case for this tag which wouldn't be equally well served by an inequality tag (which, by the way, doesn't exist on this site, indicating that this might not be a pressing concern here). As I noted in this answer, the term "inequation" is uncommon in English, and is unlikely to be understood as distinct from the term "inequality" by the majority of English speakers. Moreover, the guidance provided by the current tag-wiki doesn't seem to be about teaching or learning, but specifically about solving. While this is fixable, I think that it is evidence of a problem with the conception of this tag.
Note that this has also been discussed recently Math SE, where the same user created a nearly identical tag.