Interesting starting turned post, It appears to be early version of matching newel posts and balusters into "Family" groups. This is a group example of how a basic stair design can be upgraded to "Twisted" fittings to make a more elegant handrail system. The transition at the landing appears to flow nicely through the 90° turn. The rail cap and finial top appear to be perfectly matched with the rest of the parts.
In this picture you can see the joint that makes up the 2 piece transition from Rake to Rake Twist fitting and short section of handrail that leads up to the Rake to Level Twist fitting. This is a very classic layout and design and it appears to be well done with equal baluster spacing and smooth transitions
Looking up we can see that the handrail continues up to the 2nd to 3rd free standing staircase.
You can also get a good view of the Level to Rake Twist fitting as it transitions to make the 90° turn up the stairs.