The NRA would be the only ones to be able to advise if you are covered without doing the NSRA CRB and being an individual member, which the NSRA now require you to be to be licensed. The subtle difference between passing the course and being licensed. It sounds like you are qualified, but unlicensed. It will be down to their definitions as to what that means to them and thus you.
You may also want to fully explore the cover it offers you if you're covered. Is there a limit to the liability, a code of practice and does it cover you away from the club, and/or outside club activities?
The passing the course still stands, it's if you're covered for using it that's the issue. The NSRA aren't saying the qualification doesn't stand, only that they won't license you unless you are CRB'd and a member.
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep