Nate –
Ah, I see the source of the problem now.
While the auto generated form poses an issue, changing the rank of a node that already has dependent child nodes is paramount. Child nodes that already exist at the rank you’re trying to move the parent node to will result in the bad tree definition errors you’ve reported.
I have written a feature request (#5089) to improve the handling for this in the UI so the problem is clear to the user when attempting this.
I hope this provides some clarity on the behavior!
– Bronwyn