I am glad the plugin is working, a fightstick is a controller input I did not test. I was able to get the bumper and triggers working on my "Mad Catz Street Fighter V Arcade FightStick".
As the triggers are mapped to buttons on a fightstick instead of a trigger like in a controller, the plugin will return either 0 and 1 depending on if the button is being pressed.
Could you check if the sp_lb, sp_rb and sp_lt, sp_rt parameters are appearing in your VNyan monitor?