I just finished my final centerboard installation a few weeks ago. Not sure this is 100% correct, but here is what I did:
I did 'round' the leading edge wiht a wwod flour/epoxy mix and sanded down to a smooth curve durigthe building of the centerboard, adn 'sharpened' teh trailing edge per the instuructions.
When was fiber glassing the centertboard, I did overlap both the rounded leading edge and the shapreped trailing edge with the glassd - just used a lot of small 'darts' in the process to get the glass to lay nicely over the rounded and curved edges. My main objective was to strengthen and protect the leading edge - since it is underwater, seems very exposed, and has the potetnial of taking very hard hits from the sea bed, sunken objects, beaching, etc. I am very content that I have done my best to make that leading edge hard and water tight with the epoxy/fiberglass, and multi coats of epoxy on top (all shaped and sanded to keep the leading edge curved, and trailing edge sharp.)
I believe I will want to frequently examine the centerboard for damage since it just seems so vulnerable to hitting anything you sail over.
For the remaining 'non-shaped' sections of the centerboard (the edges between the line that raises and lowers the centerboard, and the pivot pin) I do not see any reason to overlap that all with fiberglass. Just looking at the plans and how the centerboard assembly works, those surfaces are constantly under water, but always protected by the centerboard housing. Those edges are inside the cetnerboard housing whether the centertboard is lowered completely for sailing, or raised for running, trolling, etc. So I just didn't see any need for the super strength that the exposed edges needed.
I just rounded the very sharp edges with a sandpaper block, but then made sure those edges just got 3 or 4 coats of unthickened epoxy to be completely water tight.
i just don't see any big risk on these edges of an impact, I see no places where anything will be rubbing against it, and no need for teh strength of fiberglassing beyond the strength inherent in the plywood/epoxy combination.
Not saying it is 100% right, but that is what I did.