Robbiee - the US military used the term blowback for many years to describe flapback,.and the FAA helicopter flying handbook uses exactly the same term.
Well, I've never been in the military (and they seem to have their own way of explaining things anyway which at times has conflicted with the civilian side), nor am I familiar with the term "flapback".
I'm also not familiar with the Helicopter Flying Handbook, but in my old Rotorcraft Flying Hanbook neither term is used to describe Transverse Flow Effect. If it is used elsewhere you'll have to point it out, as I only recall it ever being mentioned in the Robby POH under Low-rpm Rotor Stall.
I will admit though that my understanding of aerodynamics is on a very simple "surface level".