WooCommerce - Change WooCommerce email subject lines

gistfile1.txt

/*
 * goes in theme functions.php or a custom plugin
 *
 * Subject filters: 
 *   woocommerce_email_subject_new_order
 *   woocommerce_email_subject_customer_processing_order
 *   woocommerce_email_subject_customer_completed_order
 *   woocommerce_email_subject_customer_invoice
 *   woocommerce_email_subject_customer_note
 *   woocommerce_email_subject_low_stock
 *   woocommerce_email_subject_no_stock
 *   woocommerce_email_subject_backorder
 *   woocommerce_email_subject_customer_new_account
 *   woocommerce_email_subject_customer_invoice_paid
 **/
add_filter('woocommerce_email_subject_new_order', 'change_admin_email_subject', 1, 2);

function change_admin_email_subject( $subject, $order ) {
	global $woocommerce;

	$blogname = wp_specialchars_decode(get_option('blogname'), ENT_QUOTES);

	$subject = sprintf( '[%s] New Customer Order (# %s) from Name %s %s', $blogname, $order->id, $order->billing_first_name, $order->billing_last_name );

	return $subject;
}

hi, i just copy paste it and no result, the main problem to me is the subject is shown like "Commande reçue" instead of "Commande reçue", the letter "ç" does not appear correctly, why ?

I take it there is no function for the "on-hold" status?

Isn't there a way out there with which we can make email a little bit more personal?
I'm struggling to find a simple solution in order to include $order->billing_first_name within subject emails. It seems impossible though... :(
For instance, if I wanted to use your snippet to include a translatable billing_first_name text string for _new_order, _processing_order and _completed_order should I use a plugin or can I just tweak this code to do it?