Yes, but we cannot measure pain "objectively" at all. The equivalent would be if we could build a CPU, but could only determine how fast it could process by asking it to rate its processing power on a scale of 0 to 10.
Nothing is stopping a more technologically capable civilization from directly measuring our pain. You’re describing a purely technical limitation.
We have plenty of ways of directly measuring people‘s brains and CPU’s energy use etc. The issue is speed and resolution which is hardly a philosophical limitation.
