Alternative menu item title

alternative-menu-title.php

<?php

add_filter( 'wp_nav_menu_objects', function( $items, $args ){
	if( $args->theme_location == 'main_nav' || $args->menu->term_id == 6 ){
		foreach( $items as &$item ){
			if( $item->auto_listed ){
				$custom_menu_title = get_field( 'custom_menu_title', $item->ID );
				if( $custom_menu_title ){
					$item->title = $custom_menu_title;
				}
			}
		}
	}
	return $items;
}, 10, 2 );

// support also orderby

add_filter( 'bmp_posts_args', function( $args ){
	$args['meta_query'] = [
		'relation' => 'OR',
		[
			'key' => 'custom_menu_title',
			'compare' => 'EXISTS'
		],
		[
			'key' => 'custom_menu_title',
			'compare' => 'NOT EXISTS'
		]
	];
	$args['orderby'] = [
		'meta_value' => 'ASC',
		'title' => 'ASC'
	];
	return $args;
});