You do well with the space you have, looks like you have practice! 😀

Windows are a mystery to me. I mean the woodwork is not much different but all those details and cuts are with purpose so they shed water and keep the outsides out. 

Nice looking area! Any place green with neighbors that seem to care for their lots is a big plus in my book. 
Are you replicating the old window frames exactly? If so, too bad you can pull one and disassemble it for measurements, but then a square of OSB plugging a hole in your wall might not sit well with the conservators.

Those closet sliders look well done!