OK – the way I’ve fixed this is as follows:
In woocommerce-functions.php change the function woocommerce_add_to_cart_message and replace the variable $return_to with the following:
$shop_page_url = get_permalink( woocommerce_get_page_id( 'shop' ) );
$return_to = apply_filters( 'woocommerce_continue_shopping_redirect', $shop_page_url );
This works with woocommerce / WPML
