Although the parameter is called "gripper_force_multiplier/gripper_speed_multiplier", the parameter data is being divided by constants in the below lines. So as per the current logic, these parameters are "gripper_force/gripper_speed" and not "gripper_force_multiplier/gripper_speed_multiplier"
https://github.com/PickNikRobotics/ros2_robotiq_gripper/blob/main/robotiq_driver/src/hardware_interface.cpp#L195 https://github.com/PickNikRobotics/ros2_robotiq_gripper/blob/main/robotiq_driver/src/hardware_interface.cpp#L201
https://github.com/PickNikRobotics/ros2_robotiq_gripper/blob/main/robotiq_driver/src/hardware_interface.cpp#L297 https://github.com/PickNikRobotics/ros2_robotiq_gripper/blob/main/robotiq_driver/src/hardware_interface.cpp#L299