Actually I think machine quilting would help to reinforce those fragile fabrics by stabilizing them to the batting and backing you use. If you do decide to hand quilt an 8 wt is pretty heavy and looks best when doing the big stitch style of hand quilting. That style of quilting would be very complimentary to this almost antique top.
I would find a pretty stencil, but simple motif for doing in the yellow squares. I can't tell how large those squares are but here is a link where you can shop stencils by size.
https://www.quiltingstencils.com/Block-Sizes_c_17.html
I would then do straight line quilting in the HST that echo the yellow square. I would quilt lines right through the middle of each triangle of the HST as well as the seam line so each round of HST going around the yellow square would have 9 lines of quilting inclusive of the SITD around the yellow square. Please post a pic when you have finished.