Unifaun/Pacsoft - Add track and trace to completed email

functions.php

<?php

/**
  * @snippet       WooCommerce - Unifaun plugin by Redlight Media - Add Track & Trace url to completed email
  * @author        Redlight Media AB / Christopher Hedqvist
  * @compatible    WooCommerce 3.8.1
  */
function redlight_add_tracking_url_to_completed_email( $order, $sent_to_admin, $plain_text, $email ) {
   if ( $email->id == 'customer_completed_order' ) {
	if (function_exists('wcuns')) {
    
	       $track_and_trace_url = sprintf(
					'<strong>%1$s</strong> <a href="%2$s" target="_blank">%3$s</a>',
					 __( 'För att spåra din försändelse så kan du använda följande länk:'),
					 wc_clean( wcuns()->generate_track_and_trace_url( $order->get_id() ) ),
					 __( 'Spårningslänk' )
				);
	       echo '<p>' . $track_and_trace_url . '</p>';
	}
   }
}
add_action( 'woocommerce_email_before_order_table', 'redlight_add_tracking_url_to_completed_email', 20, 4 );