Filter register form custom fields for multiple languages

/**
 * Create a map for your custom field labels to be translated.
 * Set a new case for each language locale following the 
 * example set below. Each case should be an array where
 * the array key is the field's meta key and the value is
 * the translated text for that locale.
 *
 * Follow the example below where each array element is as follows:
 *
 *     'the_meta_key' => 'The translated value for the requested locale',
 *
 * The default value will simply return an empty array.
 */
function my_custom_translation_strings( $locale ) {
    switch ( $locale ) {
        
        case "de_DE":
            $string_map = array(
                'custom_field' => 'Benutzerdefinierte Feld',
                'other_custom_field' => 'Anderes benutzerdefiniertes Feld',
            );
            break;
            
        case "es_ES":
            $string_map = array(
                'custom_field' => 'Campo personalizado',
                'other_custom_field' => 'Otro campo personalizado',            
            );
            break;
        
        default:
            $string_map = array();
            break;
    }
    
    return $string_map;
}

/**
 * This will filter the register form labels and input tag
 * placeholders based on the translation string map returned 
 * for the requested locale.
 *
 * No changes are necessary to this filter.
 */
add_filter( 'wpmem_register_form_rows', 'apply_my_custom_translation' );
function apply_my_custom_translation( $rows ) {
    global $wpmem;
    $string_map = my_custom_translation_strings( get_locale() );
    if ( ! empty( $string_map ) ) {
        foreach ( $rows as $meta_key => $row ) {
            if ( array_key_exists( $meta_key, $string_map ) ) {
                $rows[ $meta_key ]['label'] = str_replace( $row['label_text'], $string_map[ $meta_key ], $row['label'] );
                $rows[ $meta_key ]['field'] = str_replace( 'placeholder="' . $wpmem->fields[ $meta_key ]['placeholder'] . '"', 'placeholder="' . $string_map[ $meta_key ] . '"', $row['field'] );
            }
        }
    }
    return $rows;
}

/**
 * Other filters may be used and or necessary depending on
 * actual application. This example just covers applying
 * additional translation to the register form labels. 
 * Messages, dialogs, login form, widget, those would all 
 * be separate filters. Note that you do only need to create
 * one single mapping function and you can use that fof
 * all of your translation filters.
 */