Your question is an excellent one.
I would suggest that the answer is to turn the focus away from the ballisters and to look at transitioning to the classically-detailed doorway.
I can see why the wood-turned post was used as an attempt to handle that transition.
You have a number of options open to you.
I would recommend replacing the wood-turned post with a square post that would have fluted detailing to repeat the doorway casing. You can then end your railing to this post.
This should visually solve your dilemma.

Personally I would remove the post.

It would appear you have this similar detail at the landing to the 2nd level. I think the newel post could be painted the trim color and allow the stained handrail to intersect with the painted newel post. Painting this detail will lighten this element,