Decimal symbols are currently linked to the user-locale. English setting will give a dot (.) as decimal symbol whereas the Dutch setting, for example, will give a comma (,)
This feature works on the screens/reports, but this does not happen with drillthrough values. So, in the Dutch locale, drillthrough values still have the dot (.) as a decimal symbol instead of comma.
This is confusing.
The best solution is to have the user determine the decimal symbol (and thousands separator) personally for both situations (screens and drillthrough).
But at least drillthough-appearance should be in sync with the screens.
You have some influence over the returned format in the supervision script. Additionally, also see the related idea we are considering for xlsx drill through format.