The only reason its strings are now on on GlotPress for WordPress.com is because the .org teams are going to be redefining language support for all plugins and it didn't seem fair to include Jetpack just because it's Automattic's. We don't want to have any "special priority" in relationship to other plugin authors.
If you want to see your locale and/or validate Jetpack's strings in your language, please head over to the WordPress.org Polyglots' blog and request it there.
Note: the above only applies to Jetpack. All other issues relating to WordPress.com translations will be handled on this panel, as usual.