TYPO3 Core

This issue is extracted from https://forge.typo3.org/issues/98547:

Following labels are untranslated in Site Management>Sites

1) if you try to exit before save, the dialog is not translated
Do you want to close without saving?
You currently have unsaved changes. Are you sure you want to discard these changes?

2) in "General::Variants for the Entry Point", if you try do delete a record (a variant), the dialog is not translated
Delete this record?
Are you sure you want to delete this record?

Labels and translations exist (sysext/backend/Resources/Private/Language/locallang_alt_doc.xlf) but they are not loaded in TYPO3.lang js object