In bug 1182514 we added a lightweight theme for restricted profiles. The name of the theme is not localized and is always "Parental Controls Theme". By default about:addons can't be accessed by a restricted profile and the name is never shown but a device admin can allow the restricted profile to install add-ons and then we might want to show a localized name.
I think we can close this one. We are removing this theme in bug 1222381 and I don't think we need a distinct bug to track localizing the names of the themes in the theme picker (bug 1220251).