I’m still kinda noob to WordPress and I don’t know much about working with filters, anyway U directed me what to add and its working.
THX 🙂
U can try change line 744 in SubmenuWalker.php
$p->title = apply_filters( 'jcs/item_title', $p->post_title, $p->ID, $post_type );
with
$p->title = apply_filters( 'jcs/item_title', get_post_meta($p->ID, 'short_title', true), $p->ID, $post_type );
