I'm going to be making some kuspuks for me and have been collecting various ribbons at the thrift store and running various tests.
https://www.lapassionvoutee.com/what-is-a-kuspuk/
I'd just be using ribbons as embellishments/parts of fabric, not rosettes. That would be an art piece and I don't do art!
Ribbons are not all created equal! Some disintegrate when you do more than look at them, some run like your FiL in his prime, others turn out surprisingly well. Unfortunately, it is a destructive testing technique but it doesn't require a lot.
I take a piece of prewashed solid white and I sew 2-4" of ribbon on to it with a straight stitch noting how well does it sew -- is it hard/easy, does it fray/break, is zig zag better?
Then I throw the piece in the wash and see how it comes out. I'm watching for bleeding into the white, shrinkage, and how well it held up. I'm amazed at the ones that i think will pass that fail, and the other way around too. I'm careful when I try the iron test, that's the last one. For the last test with the iron hot (and steam -- you want to throw everything you can at it), I put down a spare piece of fabric on the ironing board and position the ribbon side down, pressing from the back and I give it a good blast of heat and steam.
One of the ones I was surprised by how well it held up was a roll of wide outdoor suitable trim from Costco, it was about 3" wide, with glitter, and had the wires in the edges. I cut off lengths, pulled out the wire, and did the test and other than glitter everywhere (and still sparkling on the ribbon) had no issues at all. Not with running or shrinking or shredding. I used it for lettering on my Granny Dragon sign. Rest in Peace, this version of the XFL -- it succumbed to the flu, but I was at every Seattle home game (2!).