I don't think I am missing any point, You are talking about the mount being commanded to slew to ine position but actually reaching one that's a little different. So am I. I suggest that you re read what I posted.
Conform reports the difference between where the slew is commanded and where it reaches. That's the difference you are talking about. It also reports the two values. If you re read the Conform data I posted you will see this. Or collect some data of your own.
Or have you failed to explain what it is that you see happening? That it is not that a slew to a target position actually finishes at a slightly different position and that the difference between the target and the actual position is consistent. If so I suggest that you start again and explain exactly what you are talking about. I find that using numerical examples helps a lot.
Chris