Reports in CSV should include BOM (https://en.wikipedia.org/wiki/Byte_order_mark), so that Excel detect the UNICODE encoding and display properly non ASCII characters. Maybe it could be an option activable with syspref, or a new type of format selectable by the user (CSV / CSV_BOM).
The same remark applies to other CSV files downloadable from Kpha, not only reports.
*** This bug has been marked as a duplicate of bug 33635 ***