Sunstone issues XMLRPC API Calls under the hood. You can’t be able to issue calls with Sunstone and not directly. The errors you are getting are related to unexpected VM states when issuing those calls. You’d get those regardless of Sunstone, CLI or API directly.
The VM in POWEROFF means it reached an end state and is no longer transitioning. You use the delete-recreate option for VMs stuck in transient states, like SHUTDOWN.
In this case the VM is on SHUTDOWN and needs to reach POWEROFF before being able to have NICs attached