mickS-3

function translate_gallery($metadata, $object_id, $meta_key, $single){
    $meta_needed = 'gallery';
    if ( isset( $meta_key ) && $meta_needed == $meta_key ){
        remove_filter( 'get_post_metadata', 'translate_gallery', 100 );
        $current_meta = get_post_meta( $object_id, $meta_needed, TRUE );
        $to_translate = explode( ',', $current_meta );
        foreach ( $to_translate as $key => $value ){
            $to_translate[$key] = apply_filters( 'wpml_object_id', $value, 'attachment', true );
        }
        add_filter('get_post_metadata', 'translate_gallery', 100, 4);
        $current_meta = implode( ',', $to_translate );
        return $current_meta;
    }
    return $metadata;
}
 
add_filter( 'get_post_metadata', 'translate_gallery', 100, 4 );

if ( is_numeric( $img_data ) ) {
                    $id = $img_data;
                } elseif ( is_array( $img_data ) && isset( $img_data['id'] ) && isset( $img_data['url'] ) ) {
                    $id = $img_data['id'];
                } else {
                    $id = attachment_url_to_postid( $img_data );
                }

// WPML Workaround for wpmlsupp-12960 
                if ( class_exists('Sitepress') ) { 
                    $current_lang = apply_filters( 'wpml_current_language', NULL ); 
                    $id = apply_filters( 'wpml_object_id', $id, 'attachment', TRUE, $current_lang ); 
                }