gui.get_screen_position() ignores node’s pivot.
I didn’t know that. As result, you get screen position without pyvot and set it using set_screen_position() which uses pivot (it is set_position() with a couple of tricks inside).
The simplest solution here is using parent node for moving all nodes together (add the mto parent node, move, then remove from the parent node).
But if you want I cat add method that add pivot calculations.
UPD: I’ll fix it in the lib in a while