How did your wagon become disordered in the first place? I tried in a test scenario to disorder a wagon by moving into Abatis terrain... didn't disorder.
In that test scenario I also had about 8 DISORDERED wagons. None of them undisordered. I remember discussing this with John Tiller years ago. Not sure how a wagon could rout OR disorder. Would be interested to hear your account as to how it happened in your game.
I have never seen a wagon disorder due to a routed unit test. They are captured if an attack captures their position ....
Enlighten us
You might send a game file to Rich at the Support email to hear what John has to say about it.