Sumatra is translated into many languages but we rely on you to help us keep translations for your language up to date.
To help us translate Sumatra:
- go to http://www.apptranslator.org/app/SumatraPDF
- log-in with your Twitter account (don't have a Twitter account? Create a throw-away account which you can delete later)
- pick a language you know
- add new translations or improve existing translations
To get notified about new strings that need to be translated you can subscribe to an rss feed for your language in an RSS reader of your choice (e.g. http://www.apptranslator.org/rss?app=SumatraPDF&lang=de is rss feed for changes in German language)