The parking brake on mine is a little bit finicky, but it works. As you know from your own experience, I pull up to put on the parking brake, then can push it back down with the parking brake engaged to get the lever out of the way of swiveling the seat. But when I pull the lever back up to release it, I sometimes have to pull HARD to pull it up past where it was when I first set the brake, before I can press the button on the end to release the brake.
So if I pull the lever up too far when first setting the brake, it can be very tough to pull it up past that point to release it. You only have to pull the lever up until the parking brake indicator lamp comes on in the dashboard to set the brake, not pull until the lever can't move any more.
Also— and this is a problem for any vehicle with drum brakes on the rear— if you apply the parking brake while the drum is hot, the parking brake can jam after the brake drum cools and shrinks. It's always best to wait a minute or two after braking to a stop before applying the parking brake, so that the drum has already cooled first. This isn't a problem with rear disc brakes because the brake pads push in to brake instead of pushing out to brake as do the brake pads on a drum brake.
Engineering: Finding complex solutions to simple problems you didn't even know you had.