109 prop pitch (rpm) and the supercharger

[Crumpp]

rpm will increase as speed increases not drop, until you adjust pitch, at least my 109 does anyway lol

OOPs, yes it should increase and you coarsen the pitch to keep rpm constant.

You must maintain that rpm setting at a constant rate.
- You must pursue that (efficient) rpm setting at a continuous rate (by manual pitch)

Correct.

They are changing rpm to an overboost condition, adjusting pitch to maintain the overboost rpm setting, and then reducing it let things cool down.

When they reduce rpm, they also adjust the pitch to maintain the new rpm setting as the aircrafts speed changes.