This should normally be the case. If the Language option in the registry is not available, then pdf24 determines the language based on the OS language. If no matching element can be found, then English is used as fall-back.
Ensure, that you do not have set a language within the HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\PDFPrint path of the registry. If there is an option, than this option is used if there is no language option in the users section below HKCU.