I'd like to inform you that we now decided to switch from launchpad to Transifex to maintain the translations for Roundcube. You can find Roundcube on Transifex.com at https://www.transifex.com/projects/p/roundcube-webmail.
For quality reasons it is set to limited access which means that translators have to apply to become a member of a translation team before they can actually start translating. So if you're interested in becoming a member for a certain language team, choose the language from the list and then click on "Join team" on the upper right part of the overview page.
We kindly invite everybody to help us to keeping the Roundcube localizations up-to-date.