A new property Fillet Radius (Spline Profile->R) is added to each control point for Polygons in Line Mode (Note that all special properties are colored green in the panel now).
you can press and the drag the circle (pointing to the outside of the polygon) to change the fillet radius for each corner.
You can also select the stroke (click the stroke surface), and then change the value in Spline Profile->R. This will change the radius for all the corners.
You can also press Profile->R to reset the radius to 0.
Local Symmetry also works for this feature.
There is probably one more update for Bezier polygons/curves to add minor improvements and fixes, then I'll begin to integrate the Local Mirror and Smooth Mirror features.
[Demo Video]
https://www.patreon.com/posts/magicacsg-with-123890217
[Download Link]
https://drive.google.com/file/d/1twPM_bndxxbHkKSBnb9L8dKcARWmoMIM/view?usp=sharing