使用gettext翻译文本时出现问题

Some string in the theme I'm using are not translated and I'm using gettext on the function.php but It's not working.

This is the code I'm using:

add_filter('gettext', 'custom_strings_translation', 20, 3);

function custom_strings_translation( $translated_text, $text, $domain ) {
  switch ( $translated_text ) {
case 'View Cart' : 
    $translated_text =  __( 'Ver Carrito', '__x__' );
    break;
case "You currently have no items in your cart." : 
    $translated_text =  __( 'No tienes artículos en el carrito.', '__x__' );
    break;
case 'Shopping Cart' : 
    $translated_text =  __( 'Carrito', '__x__' );
    break;
case 'Previous' : 
    $translated_text =  __( 'Anterior', '__x__' );
    break;
case 'Next' : 
    $translated_text =  __( 'Siguiente', '__x__' );
    break;
  }

  return $translated_text;
} 

Why it's not working and what should I do? Thanks

PS My site is: https://brisaperu.com/