On the l10n wiki page is described, that the default license can be localized in jspui by adding a suffix. Looking at the code, it seems that the localized default license is only loaded in the LicenseEditServlet (I18nUtil.getDefaultLicense is only used there). During submission xmlui and jspui uses the same api method that uses this call graph and did not use the locale:
So the default license is only localized in the edit license admin interface in jspui, not during submission. Besides the documentation issue, it may be confusing that the license in the admin interface is handled different from the license in the submission process.