In ADP the key figure format in a generated file uses a decimal point as a thousand seperator (1.000). There is a business requirement to use a comma instead of a decimal point as the thousand seperator (1,000). Typically this is required when the business uses the European model based on a comma instead of the US model based on a decimal point thousand seperator.
APD uses RSCRM_BAPI. The restrictions and usage information for RSCRM_BAPI are outlined in SAP Note 605208. "Only internal format is returned for the key-figures. The system settings are not considered. Example: the decimal symbol could be , or . in the system settings. This is not considered. The value returned is in the format stored in BW."
It is not recommended to change the format stored in BW. If the thousdand seperator needs to be changed it should be handled in the APD side using an ABAP routine to change the thousand seperator symbol according to the user preference.