I really don't know what else to add here that would help you. I've pretty much given up and I let my cats walk on my counters on the sink side but I'm still trying to teach Blaze not to jump on top of my stove/oven area. Blaze is also fearless and I have to blow in his face to get him to run away from me. If I clap my hands and shout no, he'll just sit there. Now Alani is much more sensitive so if I clap my hands he's gone in a flash.

I also have the problem of both of them jumping and wanting to play in the litter boxes while I try to clean them. I've never seen two kittens that love to sleep or play in the litter boxes so much. Now I blow in Blaze's face and clap my hands at Alani and it seems to make them stay away for a little while. Oh the joy of having kittens again.LOL Good luck with keeping Jax off of the counters.

I also thought of this. Some cats hate the smell of mint so maybe you could spray something that smells minty on or around the counters. My cats hate the smell of toothpaste and mouthwash.