The tool is in reality useful only when you move/rename folders.
If this happens, then you put in the top field the old path/name and in the bottom field the new path/name (just tried it now and it works ok…).
You can also do (maybe faster):
1) close Tabbles
2) you rename/move your folder back to the old name,
3) launch Tabbles,
4) rename/move the folder to its final name
how does this sound?