I have modified the storepickup module to be used for a "Saturday Delivery" option. When the changed language file (includes/languages/english/modules/shipping/storepickup.php) is placed in the override directory, then everything works EXCEPT the module name which remains as Store Pickup.

However, if I leave the edited file in the core directory, then the module name is changed (as I intended) to Saturday Delivery

Is it me or ZC at fault?