DTS, great build. I just finished a set of curved RF7ii speakers for a friend. I'll have to try your router cut of the curved braces next time. I just made a pattern and then jigsaw and flush trimmed like you did. I ran some vertical bracing in the middle of the curved bracing to reduce the gap between the bracing. I used two layers of 3/8" bendable plywood ($30 a sheet here) and it bends very easily. No need to clamp as you go just us PL premium on all the bracing and start at front and it bends very easily while you finish nail or staple.
I use a stop strip at the front edge to butt the ply to then work toward back. I sand/cut flush with back. I put a thick layer of Titebond glue between the two sheets of ply then lay down some really cheap (Dollar Tree) drawer liner then more glue to attach to top ply then more nails. I veneer the sides then attach solid wood trim to the front edge where the stop strip was located. Works pretty well.
Build looks great and should sound awesome!!!! Great job