Wow. Lots of measuring and sewing. Not for the faint of heart! The things we do for friends!! Nice job.
Looks like a topper or valance, but maybe you have it folded up. If I remember right I used 15 yards in my panels! Had 6 panels with I think 2 1/2 yards each plus the lining. I couldn't do it now with my wrist. Take care of yourself ( pot calling kettle black-😉)
Yeah - this looks like plenty of work and measuring - doing curtains I always find it difficult to cut them straight. The pure white will look elegant in the window.
Lot of work...it is screaming for embroidery though!
I'm surprised that you didn't sneak a little embroidery on to the curtain. Must be for a very large window