I found that by reversing a black circle I can use it as a base character for white numerals using composites. The font validation reports the counter-clockwise direction as an error. Is it better to convert all these composites into simple glyphs and reverse the direction of the inner contours instead?
Nowadays all rasterizers will correctly display the outlines, however most professional fonts follow the direction guidelines.
My advise: use composites during the development of the font. When you want to distribute the font, make the final decision to convert them to simple glyphs and correct the contour direction or leave them as composites.