I think there should be better description how to shape that "cover". In my own surveys from std low drag cars that last pointing edge should be measured so that if you put some straight thing tangential to the last edge, that part thould touch the wipers upper edge.
In my opinion your version looks like it deflects air too much up which will cause the air to become "turbulent" and flow backwards. In my seat I did tuft testing and first my "cover" was too high and that happened. When I carved it so that air will gently touch the wipers air direction changed.
10062009571.jpg - Windows Live
Pictures are there. and the last one is how it should be
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17062009587.jpg - Windows Live