I have a cge-pro with the latest celestron driver. The behavior I describe follows from discussions I had with the firmware writer in the teamcelestron forum. I am puzzled that people would be surprised that a mount could very quickly slew to an exact encoder position, while swinging large weights around the sky.
Celestron mounts use to have a feature called "calibrate GoTo" that would account for different payloads in the timing needed to do a slew accurately - but the firmware has changed and I don't think it is supported.
I always use a mount model based on about 6 total stars - because it is very accurate and allows pointing across the sky with about 3-5' accuracy. Given that the accuracy is not perfect, it is somewhat acceptable to allow some error in the SlewToCoordinates, in terms of the final ra/dec encoder values not matching the intended target. The net impact on GoTo accuracy is small compared to the mount model accuracy across the sky.
In some sense none of these details matter. A human looking at centering logs for my mount and many others will show the initial slew to have error, and the second slew has much less - but it does not improve after that. I have seen that many times for many reasons.
The obvious thing a human would suggest is - why not just aim a little down and to the right so that it hits the target? That is a few lines of code and it makes many issues go away for many mounts - and removes the need for sync. But if you want to sync you still can.
Frank