Don't really understand idea. What like Pinta starts up and looks for translations file on web and if available then download, is it?

I don't think this is the best solution. Pinta project has to establish some kind of project plan and in one of the last stages it should have a string freeze when translators are ready to translate (and no big string change is planned). So when Pinta is released there should be equal quality available for English and non-English languages.

I'm afraid we can't do this, both because of the string freeze that grofaty mentioned and because most Linux distributions like Ubuntu demand that translations are static once a release is made and that all updates must go through the package manager.