You still have the ability to change the default language of your site once you have started translating. This can be done by navigating to your Site Settings on the right drop-down menu and selecting a different language on the Current Language drop-down menu.
However, we do not recommend this as it may affect all translations that have already been completed on your site. This should only be done in extreme circumstances. Please contact us at support@localizer.co if you have any more questions regarding changing your current language.