TYPO3 v9 has reached its end-of-life September 30th, 2021 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.
You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.
In the Install tool, go to the module "Maintenance" -> "Manage languages" and update your translations. If you don't update your translations, new texts will only be displayed in English. Missing languages or translations can be added following the section Internationalization and Localization.