Stool nose and the angry 1/2"

Insomnia. Which means I can't turn off my brain. Which means I get obsess about things I normally don't have time for. 

 Take our newly installed master bedroom window trim (original on the left. New on the right). Looks great, right? Except that since the day he finished installing it, I've thought something looked off. Tonight I figured it out. The stool nose extends too far past the edge of the casing. By 1/2". It's my fault. He asked how I wanted it done. I pointed to one of the only two windows in the house with their original woodwork fully intact and said "make it look exactly like that". 

What I should have told him was the exact formula to use in order to get exactly that. Just like every other piece of woodwork in this house, they didn't just eyeball and cut what they thought would look good. Everything is the size that it is and cut the way it was cut using formulas that produce a well proportioned finished product. It's bad enough he mitered the returns rather than coping them with a hand saw like the originals. Now all I see this useless 1/2" that's begging to be cut off.