If you'd like to contribute to the official translations that will ship with paint.net 4.0, I've set up a crowdin project for this. The project's URL is https://crowdin.net/...ect/paintdotnet
I've never used crowdin before so I don't know how I should "invite" people to participate, or how to organize it at all So let's do it this way: if you'd like to participate, please post here with your crowdin user name and the language you'd like to help with.
Updated translation files (RESX files) will be picked up before each release and used as-is as long as they pass ResXCheck validation ( http://forums.getpai...ore-publishing/ ).
Any new strings added to Paint.NET will default to using machine translation. It'll be up to translators to provide better text (if necessary, which it probably is) in time for any public release of Paint.NET. I will not delay any release for the sake of translations. Thankfully this is the Internet and so there's always another train coming, so to speak.
This is currently an experiment. I don't know how well I like crowdin just yet or how well it'll work etc.