I tried to attach a short video but it didn’t work. (Apple user) I have read all the threads about the kinematic lever and clutch bleeding. My issue may be related to that but I am not sure. So here is the problem. My clutch returns fully as expected. However once the pedal is fully up it slams into its up position making a loud thud. In others woords if you take your finger and push on the pedal and take up the minimal free travel and then let go it snaps back hard and thud. It is so forceful and loud I initially thought something was amiss under the car. The car is a new to me 1995 C2 coupe. I tried WD40 to see if it was just sticking a little. It didn’t make any changes.
The car is a bit of a rescue. I just completed rebuilding the rack and pinion and am about to replace the front arm bushes, ball joints, tie rods, and struts. I had to replace the carpet and sound deadening and the interior as well. Once done with the front I planned to start on the rear. Bushes, arms, struts, the pedals are a bit of a question mark for me.
I also tried adjusting the adjuster screw it made no difference to the forcefulness of the pedal slamming forward on its stop.

I’m working on my kinematic clutch lever right now and after taking the entire pedal box assembly apart, my best guess would be the spring tensioner bolt (which you mentioned - but perhaps you need to back it out more?). If not the spring tensioner, then possibly the main spring itself or the master cylinder? Hopefully someone with a better understanding will chime in.

I was thinking the same thing (rubber stop) it doesn’t seem to have one. I guess I am just gonna have to pull it out and see what is going on. It definitely is not a smooth action. It kinda gets to a point and then breaks over hard resonating thru the car floor.