Theme options is something I've been considering for a while, Jatin had a plugin for the SnowFlat theme where you could change the colours, which would work better as integrated theme options.
Having said that, adding a separate unique button is more of a plugin concern than a theming concern. You could make a widget or layer plugin that adds the button, and utilises plugin translations. Or a simple module with only the admin_options function where you set the language strings in options, and use those in the theme class.