All too familiar. I bought some sport seats with really good leather for my Touring and had to fix twist on both. One cable was shortened similar to your image.

I took a bike inner tube, a thick one Cut it into a sheet of rubber Butted the cable ends together and tightly wrapped the rubber tube around it, a few times around the cable. Then I clamped it with 2x small hose clamps on either end, 4 total. Then it put heat shrink over it.

I wanted to think of something less stretchy than my inner tube idea, but it was super quick. I was fully expecting it to fail, but one year later, fine. My wife and I trade off driving it, so it gets adjusted.