Ok, I could replicate with backup-aaa_esempio.mbz, but then when I tested with a test course I created with one restriction and used the same CSV format then it worked. So, when restoring backup-aaa_esempio.mbz manually I get:
Invalid get_string() identifier: 'pluginname' or component 'reservation'. Perhaps you are missing $string['pluginname'] = ''; in mod/reservation/lang/en/reservation.php?
line 353 of \lib\classes\string_manager_standard.php: call to debugging()
line 7298 of \lib\moodlelib.php: call to core_string_manager_standard->get_string()
line 202 of \backup\util\ui\renderer.php: call to get_string()
line 384 of \backup\util\ui\restore_ui_stage.class.php: call to core_backup_renderer->backup_details()
line 163 of \backup\restore.php: call to restore_ui_stage_confirm->display()
therefore I suspect that because mod/reservation is not installed this causes the problem.