Hi there,

1 - In this old version, dimensions are orthogonal and surfaces consider the angled sides.
2 - The issue is the room space definition => The room dimensions (label) show the dims between the axis of the walls. If you use the wall to wall dimension tools show the distance between the surfaces of the walls.

A workaround:
1 - Click in the center of the room => deactivate the label (Name, Dimensions and Area)
2 - Go to the Detail tab => using the polygon shape => outline the desired area (Kitchen, for example) => select the polygon => Properties bar => calculate area
3 - Using the dimension tools => take the room dims.
4 - Using the Text tool => Add the desired name, dims and area.

Hope this helps.