Sorry for not replying so far. Thanks for the feedback! Right now I can't really find time to fix the patch. Maybe someone else can pick up this bug?
Here's a screenshot of the reference Gerber viewer (https://gerber.ucamco.com/) rendering the example above: I also attached another file that can be used to test the rendering. This is what it should look like:
Fix handling of single-quadrant arcs (G74*)