Leonardo,
I have already worked out the CSV option and did fall back to using that method. I ran across this error as I was exploring how to create the import data set in Excel format. What is odd is that creating the worksheet with the data is easy enough but I can only get the import to work by copying in a Workbook Manifest sheet from a Excel file that was created by Syncrosim. There is something going on behind the scenes in that Workbook Manifest sheet that is not obvious to me. I was kind of hoping for some enlightenment on what Excel magic was happening.
On a side note another option that I have explored is just doing a direct database to database conversion. Python has drivers for both Access and Sqlite formats. I have done written some code that explores that method.