To find back to the connected mode in case of inconsistent content ("mixed mode") it is an editorial help if the unique id uid of content elements in the selection field "Transl.Orig" tt_content.l18n_parent is displayed regardless of whether debug mode is activated and the admin status of the backend user.
To achieve this, place this file in your sitepackage under: EXT:sitepackage/Classes/User/Tca.php and add the following line in EXT:sitepackage/Configuration/TCA/Overrides/tt_content.php:
$GLOBALS['TCA']['tt_content']['ctrl']['label_userFunc'] = Tca::class . '->labelWithUid';
This user function returns the title considering the tables ctrl settings label and label_alt since it uses exactly the same function BackendUtility::getRecordTitle in the first step before appending the uid.
If the backend user has the admin status and the debug mode has been activated, this user function has no effect on the output, since the uid is already displayed after the title by default.
If required, this user function can also be used for other tables. To achieve this, simply replace tt_content with the name of the table.