What does the following return for you at the AutoCAD command line?:
(vl-registry-read "HKEY_CURRENT_USER\\Control Panel\\International" "sList")
If the above returns a semi-colon instead of a comma, try replacing the commas in your CSV file with semi-colons.
Alternatively, if you want to continue using a comma in your CSV files, replace line 300 of my program with:
(setq sep ",")