I bet, Dutch fly on the red side
There is no analog prop pitch adjustment in the 109. Even if you set to axis. The analog axis will be work like a big, slow, annoying switch - One-third of the axis: PP down, PP stop, PP up. There is no direct connection between the analogue axis position and the prop pitch angle.
So, you have to set the PP to a button. I recommend one of the throttle HAT switch up and down positions. This is the most "historically accurate", after the auto PP installed, the 109 manual PP switch was placed on the throttle.
I dont understand your question, how can u mapping the keys? Double click in the controls, then push the hat switch. It does not work for you? No need to know the name of the buttons. The program will know