Like it or lump it, the overwhelming majority of people out there using the English language, who have even the slightest musical awareness, wouldn't have a clue what the 1954 definition is all about.
I found traditional song, completely *independently* of 'folk music'.
I was never a 'folk music' fan, if I thought 'folk' - just like everyone else (bar a tiny minority of specialists) - I thought 'Dylan' or 'Steeleye Span'. I didn't like folk music, so I never bothered with it, and as a consequence Trad Song completely passed under my radar for terribly long time.
The term has been utterly lost to whatever it initially meant, and as Leadfingers put it, has become an 'Umbrella Term' for a very broad and eclectic musical genre.
If you want to communicate to the real folk in the world, you need to speak their language, otherwise they will neither know nor care to know what you're attempting to say. And especially if you have to refer them to some academic definition for disambiguation of a term, which is completely inconsistant with the everyday language that they use and do understand.
In fact I'd prefer to see 'Traditional Song' move out from underneath this weight of miscellany, and stand on it's own as 'Traditional Song' because, if my (and that of some of my peers) own experience is anything to go by, 'Traditional Song' is vastly overshadowed by the volume of material out there proliferating beneath the folk music umbrella.
Traditional song, has become completely lost beneath such an expansive term. No-one in the real world has ever heard of the 1954 definition, but they *do* understand 'Traditional [insert culture and art or craft as applicable]' as a term that is used in a variety of contexts in a fashion that is overall pretty consistant and stable, and not requiring any form of disambiguation.
Trying to retrieve the term 'folk song' is IMO doomed to failure, and a complete waste of energy which could be far better spent, promoting broader awareness of 'Traditional Song.' Fair enough if you are speaking to those who share your sympathies and specialist understanding, but IMO it's alienating, confusing, tiresome, and can in no way further the cause of increasing greater public interest in and knowledge of Trad Song.