The TWS Plugin will by default save logs in the TWSLogs folder in your RightEdge application data folder. Those logs will probably be helpful to figure out what happened with the order. You can also send them to us if you don't figure it out yourself.
Right now there's not a way to modify an existing order. You have to cancel it and resubmit. RightEdge will do this for you if you call the SetStopLoss() method on the Position.