Thank you, I'll try FPC 3.2.
I perhaps found a workaround :
Before : RunCommand('aprogram.exe',['"'+FileWithSpaceAndAccent+'"'],S,[poWaitOnExit, poNoConsole])
After : RunCommand('aprogram.exe',[AnsiQuotedStr(UTF8ToWinCP(FileWithSpaceAndAccent),'"')],S,[poWaitOnExit, poNoConsole])