Transforming all the changed actors by hand tags them as changed and any changes (as my set materials) are being queued. As Datasmith links any imported static meshes to a DatasmithSceneActor I can move those scene heads back and forth and it triggers their whole hierarchy as changed.
Editor utility widgets changing scene actors don’t tag the actor as changed to WorldPartition. Seams like a bug or bad design choice.
Looks like only user changes by hand trigger the “is changed” actor status.