Actually, the problem is another.

You can see what is happening in the saveTransform function in transfom.c.
If proportional edit is enabled during a transformation, this option is updated in the scene.
However, as the Cursor does not use this option, the code mistakenly sees this as if that option has been disabled and thus updates the scene.
If a value for "use_proportional_edit" is set, this update is skipped.

I have an idea of a different solution that makes the code safer and simpler.
I'm working on it.