Good post. Honestly, I've pretty much stopped worrying about cones altogether. I don't low-poo daily, and I alternate between GVP Conditioning Balm (no cones) and Davines Love Smoothing (LOVE this condish!) which has 2 cones --neither of which are far down the ingredient list. If cones really aren't objectively harmful for hair (someone's hair not liking cones is a different story), and I don't believe they are, then it shouldn't matter how far down the ingredient list they are.
Buildup is a different story, but I've gotten plenty of buildup from "CG" conditioners and stylers when I was co-washing, so what's the difference between silicone buildup and other types of buildup? You still have to get the buildup out of your hair with a shampoo. I haven't gotten any buildup since introducing the Davines into my routine, and I only use a low-poo twice a week. I do clarify every 6-8 weeks, but that's because I henna every 6-8 weeks and I like to make sure nothing interferes with the color deposit.