Thought so too but if you put screw through flat side doesn't it only go one way or am I wrong?
Not really understanding your question.
If my memory serves me, when I got to the point of connecting the camera to the pitch motor shaft, I was fairly certain that the screw enters from the rear hole in the camera housing, and
to me it seemed logical that the round side of the pitch motor shaft would also be to the rear so the screw would pull the rounded shaft into the rounded housing, and they would nest.
Started it up and the gimbal was wonky.
Watched some videos and from what I could tell, I had it wrong. So I took it apart, rotated the pitch motor shaft 180° so that the flat side was facing the rear of the drone, and I still put the screw in, entering from the rear.
I cannot say with 100% certainty that I have the screw in correctly, but if I do, I cannot understand why it would be designed that way.
Edit
Just watched this tutorial:
>>>>LINK REMOVED! sorry, for some reason I can't get a working link here <<<<
which confirms what I am explaining.
If you watch it, scroll forward to 11 minutes where he takes the camera off and reinstalls it.
2nd Edit
I think I just got your question.
Are you asking if the screw can only enter the pitch motor shaft from one side?
No, the screw will thread in from either side.
Just like a bolt/screw with a nut. You can turn the nut around and the screw/bolt will still thread in.