One push then it's all over, to create 120 uJoules to send 1 packet of a digital code to a paired receiver. ISM Band of frequencies of transmission. 868 0r 915 MHz.Not if their pulses are more frequent. What of they can run at 1kHz?
We are still just guessing at the overall application you are dealing with. Better questions get better answers.
Firstly, the energy harvesting generators (EHG) in question perform the task of replacing an electromechanical wired-in switch with a battery-less and wireless version. The transmitters are powered by these EHGs.Is that 200 msec with 23 volts......or 200 msec for 23 volts to fall? Why not clearly explain and show us what you're doing. You starting question was about efficiency.....but we don't know what to compare it to....except those figures.....without context.
You seem to know what you are comparing....but we don't. We need to know specs on other device too.....not just yours.
So our answers will be out of your context.....til you share your context with us.