Thanks to Amidar for this Serbian language pack for Phrogram!  When you unzip it into the Phrogram install folder, it will replace the "New Program" snippet with a Serbian version.  It also places a .RS version of the KPL.StringResources.XML file onto the disk.  If you rename the existing one to KPL.StringResources.EN.XML and then rename Amidar's KPL.StringResources.RS.XML to KPL.StringResources.XML, this will replace the IDE UI strings and error messages with their Serbian translations.  Just restart Phrogram to see that work after switching the files.