result = connection.execute(new CheckoutCommand(cartCode, ccv), hybrisService.getBaseStore(), this);
java.util.Map ids = parser.parseIds(result);
orderId = (java.lang.String)ids.get("guid");
throw new CommerceException("Order guid missing");
orderId = (java.lang.String)ids.get("code");
throw new CommerceException("Order code missing");
So I can understand that you may need the 'guid' to get at the order details of an anonymous Hybris order. But even in that case I would display the regular orderNr to the customer and use the guid to construct any URL for requesting order information (if even necessary).
As this is a hybris specific class, it seems strange to not also have a hybris specific 'guid' field in it which you can set in case of an anonymous order. If it is filled you can use it in the communication with Hybris where needed, but always show the proper order number to the customer I would say.