@helpmeplease I think you can have the accounting format in knime only as string since knime will use its own internal storage of numbers. If you want to have this format in Excel. Maybe the way to go forward would be to just export the regular numbers and then change the format in Excel:
Another approach to this could be to use Python and Openpyxl like this - but maybe you start with the Continental nodes. I can see if I can come up with an example.