Personally, I have always believed that The Child Ballads cover such a wide area of the English-speaking (and beyond) world that it would be virtually impossible tp create a representative musical file of the collection, but it might be possible to create national files (in the cse of the U.S., even that might be too large an area because of the varying styles across the country).
When Child put together his collection, Ireland featured very small, but when collector, the late Tom Munnelly, was working in the field he listed 50 Child Ballads still extant in Ireland, some having totally disappeared elsewhere - that was from oral sources only - Tom never touched those in print.
Recently, I have been gathering together recorded Irish versions of the ballads with a view to providing as many examples as I can of them.
Maybe that's the way ahead to compile a comprehensive set of examples - break down the job in areas - and maybe Mudcat is as good a place as any to centralise it.
Jim Carroll