You don't need to customize the `xhtml` pages for localization. Also, I see you are modifying temporary files. These modification will be removed once `oxauth` restarts. So, If you want to localize/change the `login page` permanently, Please follow this [documentation](https://gluu.org/docs/gluu-server/4.4/operation/custom-design/).
Following procedure to change `username` text from login page:
1. Download this [resource](https://raw.githubusercontent.com/GluuFederation/oxAuth/master/Server/src/main/resources/oxauth_en.properties) file and put inside the `/opt/gluu/jetty/oxauth/custom/i18n/` directory.
2. Edit `oxauth_en.properties` file as your own.
3. run: `systemctl restart oxauth` to restart `oxauth` service. It should display the changes at login page.
Regards ~ Shakil