You can also extract the polish language from another region using main2raw and sefstool4. There are some tutorials out there but I haven't had luck using this method it always gives me errors. :( I really would like to install Ukranian language onto my k790 but I'm not going to reflash and lose all my patches and my polish language also :( I have a post up asking for someone who has a working software with these files to extract them for me... and maybe someone can help you also. I wish I could figure out why I'm getting those errors though. But yeah, if you want polish and no one will help, flashing your phone with the proper region is the only way.