If you hud-object is on a layer without paralax it's coordinates will stay the same..
Maybe you can get what you want using these expressions:
CanvasToLayerX(layer, x, y)
CanvasToLayerY(layer, x, y)
Calculate the layout co-ordinates underneath a position in canvas co-ordinates for a given layer.
LayerToCanvasX(layer, x, y)
LayerToCanvasY(layer, x, y)
Calculate the canvas co-ordinates above a position in layout co-ordinates for a given layer.