No need to do a course to be an FTE
There are many FTEs in the world that have never done a 'recognised' course, but have gained experience in the world of Flight Test in industry and carried on to run major (and multinational) projects from initial flights to out of service.
As with any responsible job you allocate properly skilled people to do the activity, and that may mean much more than a paper qualification. In the Flight Test world experience is the most valuable asset you can have.
DM