I agree that the 1954 definition is probably adequate for 'traditional' music.

However, because of its emphasis on the 'creative process' (oral transmission etc), failing to foresee the rapid changes in recording/storage technology of today (or indeed of tomorrow), it falls short as a definition for what came/comes after.

I've always found the concept that a song must change before it can be accepted as a folksong as rather bizarre. If, in 200 years time, people still sing a Bob Dylan song unaltered then, IMO, that's still a folksong. (BTW I chose Dylan deliberately because I don't happen to like his music).

I am not going to suggest an alternative definition because that too will become obsolete in time. Let's not repeat the mistakes of the past.