The language translations for the Joomla 2.5/Joomla 3.0 version are maintained at Transifex. Transifex is a tool to manage translations online, and Joomla language files can be generated from Transifex.
You can add a translation for the gallery, or help with an existing translation, by joining Transifex, and adding a new team or joining an existing team. You can do this here. If you do this, please email support, so we know who you are, and we will also refund your purchase and give you free updates.