My view is that "trad" means the communal part of the folk process whereby a song is changed from it's original so often that it becomes a part of a specific folk tradition or an even more general one such as found in a contemporary folk sense. IE: Wildwood Flower which was originally a composed song from England and changed by the Carter Family. Angelina Baker would be another. Most all of the Appalachian dance tunes have origins in minstrelsy and British Isles and have been appropriated and changed with new verses and tunes added.

Anonymous just means that the author or composer has been forgotten or is unknown and the work is unattributable to them.

Frank