Adjust the section mark position to the midpoint of the cutting line

Can Rhino Inside Revit adjust the section mark to the centerline of the section, a task that can only be done manually in Revit?

Correct, What you are doing manually is not exposed in the Revit API

Can we achieve this in Rhino.Inside Revit?

Rhino.Inside.Revit interactions with Revit are limited to what they expose via the Revit API, not all things you can do in the Revit User Interface can be integrated. You can’t create a scopebox for example, that method doesn’t exist in the public Revit API but is a simple exercise in Revit.