Revert "Fixing internationalization codes"

This reverts commit b5dd581fbe18b76285b36e56e5916a1bba19a428.
Revert "Fixing path to i18n directory"

This reverts commit eba5d194f270a53ef8cc2eb07cf5ca3af981e7c7.
Adding tests in case of invalid internationalization code
Some refactoring and fallbacks in internationalization