I am afraid I don't know whether Garble was a dryad or a naiad, as there were both streams and trees near Jack's farm.
Ordinarily, he would have brought it to Jack, but thanks to Garble, he didn't dare.
Since Garble was far away, he fixed it with no problem whatsoever.
Without Garble around to confuse things, Jack and the farmers were able to understand each other quite well.
As long as Jack stayed out of Garble's reach, he and the farmers understood each other.