I tested just now with (to make sure there were no regression):
Code:
sony_playstation_r_3_controller_button_8 = action_joy_0_fire_button
sony_playstation_r_3_controller_button_9 = action_joy_0_2nd_button
and it worked like expected. Note: you should use your second example. The "long" joystick names are not supported for these mappings.
Please post FS-UAE.log after a failed attempt to make it work, for analysis!