A Church proclamation is official worldwide if it is a deliberate teaching of a Pope, an Ecumenical Council, or an Office of the Vatican. There is a hierarchy - an Apostolic Constitution from a Pope, for example, is “more” official than a Papal Bull (it is viewed as a more solemn teaching).
The teaching on premilleninism that I mentioned was promulgated by a Vatican Office that I had not previously heard of, but it’s official because it came from the Vatican.
Regional proclamations are official for a certain territory if they are promulgated by a regional Council of Bishops (a mini-Ecumenical Council), a Congregation of Bishops (which is a standing Council), or the Bishop of a Diocese (or the Offices of any of these authorities).
Only a Pope or a General (Ecumenical) Council MAY teach infallibly (though they usually do not). Being official does not mean it is also infallible, so most official teaching has not been infallibly defined.