I think the reason that the Telemann Catalogue is so convoluted is because
its the work of several editors.  The task was just too much for one person
to have accomplished.

That pretty much ruled out a consecutive number sequence cataloge such as
"BWV" with the works of Bach, or "K" with the works of Mozart.  The only
category you are just awed in the Telemann Cataloge by the sheer volumue
of work is the cantatas.  They number past 1500.

Kim