What is an "Organizer" account?

No source beyond the fact that that is the verbatim verbiage Windows offers when one clicks thru the option (apologies that we don’t have the ability to screen capture at the moment). The important takeaway is that in this context the semantics really matter. It would have been tempting for the team working on family safety to call these family safety users “Administrators”. But family safety features are becoming increasingly (and increasingly seamlessly) integrated into the Windows OS. This presents a challenge when, as you experienced, these features are going to coexist in the same space as things like the Account Settings on the local machine. In that context it’s critical to make a distinction between an account with Admin rights on the local machine vs. an “Admin” on given Family Safety features group. For this reason (and others) the team needed to choose a different term - they chose “Organizer”. With this distinction drawn it’s much easier within the context of any given local machine to clarify when a local Administrator account also happens to be a Family Safety group Organizer account, or not.