@may027 -
I wrote down some information, then went back an re-read your statement. I went into a beta version of my course and played around with the assignments in the grade book. From your statement:
I still don't understand this about exporting the Canvas Gradebook: assignments that are graded but hidden from students are not included in the Final Points (read only) column. That is despite what I read here which implies, at least to me, that the hidden scores are included in Final Points.
Am I missing something? Do I have to post grades before they show up in the Final Points?
I am seeing exactly what you see. Current points shows the score for all scored and visible assignments. However, Final Points shows the same value and does not take into account graded assignments that are hidden. I would have to assume that is a bug in Canvas, but I am not sure. So in answer to your question about them having to be posted to show up - as of the current configuration of Canvas - yes they have to be posted(visible to the student) for them to show up in the Final Points column.
As for your second part:
Edit: to add to the confusion I just discovered that Current Score (percent of total points) does include hidden assignments, as noted in the linked support page. Why are the hidden scores not included in the points total?
You may have mixed up a little of what you are saying - or just the presentation. the Current Score is the percent grade of all graded visible assignments, and the Unposted Current Score is the percent grade for all graded assignments (whether they are posted(visible) or not. So the Current Score and Unposted Current Score calculations work as described (and expected).
Ron