@sovainfo @infograf768 Just wondering on this one: Do we even need this whole function. We don't have categories in com_tags and no submenus. So this function serves no purpose to begin with.
Also it tries to load itself on the next view lines. Doesn't make sense to require_once the file which is currently processed.
Also the TagsHelper::addSubmenu('tags'); in the tags view isn't needed at all since we don't have a submenu.

Do I miss something?

@javigomez It came from com_categories. It is duplicating that trick of not running when called from the component itself.

Nothing to do with categories, only using the same trick. Currently only used from the component itself, maybe 3p extensions use it. It allows other components to provide language strings for tags.

But then this should probably be changed as well?
$file = JPath::clean(JPATH_ADMINISTRATOR . '/components/com_tags/helpers/tags.php');
to something like
$file = JPath::clean(JPATH_ADMINISTRATOR . '/components/' . $component . '/helpers/tags.php');
since trying to load itself just doesn't make sense.

If we copy that from com_categories, we should copy the whole thing correct.