Jesus and Mary are Impeccable. All Ecumenical Councils are Infallible, it is intrinsic to their nature. With all due respect, it is you that is confused. Try to find any Catholic, traditionalist, modernist, conservative, that has ever described an Ecumenical Council as "impeccable."<>
The concern is with the misuse of the definition. Not the use of the word itself. Surely you understand that.