I tried doing your thing and mapped my left and right brakes to the slider on my throttle. When I put on the brakes using the slider I don’t get any brakes until the slider gets to the end of its travel. Then it grabs just like the trigger brakes and I nose over. On your setup, if you move the slider half way do you get brakes but with half as much pressure? On mine I get no brakes until the end of slider travel then full brakes.