If you explicitly define the report to separate with a comma, it should absolutely use that, not the end-users desktop default. It surprises me that this seems to be happening. The Help text for the CSV Separator field says:
"Identify a column separator. If no value is entered, a comma or semicolon is used depending on your current NLS settings."
So I'm wondering if you've set that value or left the default?
How do I exactly define the separator?
Because it is a default action in a report; users just go to Actions > Download > CSV.
They don't have the option to provide the separator.
I also can't find it when I edit the page...the only thing I could find is under application properties > globalization settings > Automatic CSV Encoding
And there you can't set the separator.