SIDRA INTERSECTION reports and displays use the Decimal Separator that is defined in your Windows settings, except for the Detailed Output where a point is always used.  

You can change the Decimal Separator in Windows under the Region settings section of the Windows system settings.

For example, in Windows 10, go to Control Panel -> Region -> Formats and click Additional settings… at the bottom of this tab. In the Customize Format dialog, Numbers tab, select the desired Decimal Separator under the Decimal symbol dropbox.

You must restart the computer after this change is saved.