For dimension "Currency", please keep in mind the dimension currency is the transaction currency. Currency dimension can be used only with the Transaction Currency measure. It does not make sense to use it with other measures ( such as Group Currency...
Could you please check KBA 3515248 FAQ about scope item 3AF and Group Chart of accountGroup reporting have nothing related with Group Account for each G/L of YCOA.
Sorry this is an missing feature in current version. just like KBA 2646756 - SAP Group Reporting Data Collection - Limitations and Known Issues https://me.sap.com/notes/2646756 " Known issues to be fixed for multiple periods and multiple fiscal years...