undo the reference creation and redo it - the transform and also the child->parent relation is wrong now
You also get two transform states when creating a reference, this also isn't correct and only happens when creating the reference (in the viewport when holding shift and translate the object) - this doesn't happen when you use the viewport gizmo to translate an object without creating a reference.
commits between f5462ff8bc2a08bffa827be4c9e0280dbce98a01 and 123bef8468dcba3207981633cd9711d01f16ad5f improved the MementoHandler and also fixed this and many other issues
undo the reference creation and redo it - the transform and also the child->parent relation is wrong now
You also get two transform states when creating a reference, this also isn't correct and only happens when creating the reference (in the viewport when holding shift and translate the object) - this doesn't happen when you use the viewport gizmo to translate an object without creating a reference.