Upon a quick look, I discovered that the calculation in question directly converts from Revit internal units (Feet square) to meter square, aligning with a third-party calculation found here: Metric Conversions.
However, if we convert the radius (in metric) to feet, which equals 4.265, and then calculate the area of the circle, we arrive at 57.14627721 ft². Converting this value to square meters yields 5.3017 m².
My understanding is that Revit focuses on the shape of the geometry, disregarding the drawing principles the user employed to create a 3D model.
good catch by the way

Moustafa Khalil