Ah ok. Decent FMIC.
This is true. Sharper the edge/corner in the combustion chamber the hotter it will be and can be the source of a hot spot that may cause knock.I was looking at the cylinder head photos. Your engine builder may have different opinion but I would at least discuss with him removing the sharp edges near the spark plug holes. Sharp edges anywhere in the combustion chamber tend to get very hot and act like glow plugs.
This makes sense.It's no longer a sharp edge when the spark plug is sitting in place, it's up against the spark plug thread.