The 'left' and 'right' terminology for windows is not very good.
The problem is a windows direction is chosen by the last click when placing the object.
So it should really be 'side 1' and 'side 2' or as I refer to them in my window objects 'placement side' and 'other side'.
So the placement side (left as the window is scripted) can be on the left side of the opening when placing the window or the right side of the opening as you have shown in the image you attached.
They are the same window but one is mirrored so the left is on the right and vice versa - but the left side now on the right is still referred to as the 'left' side.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11