That's correct. The relationships between the tail and wing would be based on some design speed. You can expect trim changes with speed, but a Cessna changes trim with speed too. I don't know if the Pfalz had trim tabs on the elevator, but I would assume it did. So you could trim for different flight speeds. My guess is the tail was designed so that the speeds where the tail started to self correct would be higher than the plane could obtain in level flight but (obviously) lower than the max for the airframe.