Hi Julien,
I had same problem. You can solve it in one step:
Go to \plugins\wpglobus\includes\class-wpglobus.php
In line 1807 or search for the next line:
$item->menu_item_parent = 9999999999;
You need to change the value to zero. After you saved it, WP menu function doesn’t put extra languages to submenu. In CSS you need to apply some margins or something to separate flags.
Sincerely,
Noge075
