With the "Xbox Extended Feature Support" option selected, you actually can map individual keys to paddles within steam. The problem is Steam Input/BigPicture has been incredibly unreliable for me within the past few months. I'm just glad I can make changes using the first-party software now.
Edit - saw your edit. Changed the post title to make it a little more clear
There’s constructive criticism and then there’s
Coming from ffxiv, YoshiP knows what actual grievances are and what troll comments are. It’s not a “reality distortion field” to call jackasses, jackasses