What is the name of the book we always refer you folks to (besides the CE)? The full title is "The Catechism of the Catholic Church" If they were to need to use "Roman" as their official title it would be used there, I would think.
When people do use "Roman" it is to avoid cofusion with other churches, or to avoid offense. I don't know where trad_anglican is , but he would take offense in my saying we were "just plain Catholic." He thinks his Church is Catholic as well and that we need to add "Roman" to our name to distinguish the "Anglican Catholic" from the Roman Catholic." We may use "Roman" in certain situations for clarity, but officially it is not our name.
Others like to think of the Catholic Church named in the creeds as the "invisible" Church of all believers. They also take offense at an unmodified "Catholic" being used by us.
Inside of the (Roman) Catholic Church, the term Roman often refers only to the major western rite, or Roman Rite. There are other Catholics who are not Roman at all, other than in allegiance to the Pope. Byzantine Catholics and the other eastern Churches are not "Roman." I am a "Roman Catholic" in the sense that I am a "Roman" or "Latin Rite" type of Catholic.
SD