Qanba R4RAF stick/buttons Sensitivity question

You can replace the stock spring with a stronger one, I believe Focus Attack and Paradise Arcade Shop sells them. They vary from 1.5lb all the way 9lb. Another thing to test is replacing the actuator with a 0.5 version.

When I changed my plungers from my obsc to some clear ones that I got from PAS they did change how they feel considerably. So the plastic does change how the buttons feel.

You have to factor in every stick has a different level of wear and tear on its joystick and buttons.
New sticks can be feeling either too tight or too sensitive.

Also different batches of the same Sanwa parts can have a completely different feeling.
Different colors of plastic cools off and expand differently also throwing off their feel.