The only current way to automate One Note is via the screen OCR methods. That will be especially challenging to automate an entire app this way and would not likely be reliable. I would say this is an app that cannot be automated at this time solely with Pega Robotics. That being said, it appears as though you can use UIAutomation in C# to do some of the things you mentioned. You could call that from a script inside of a Pega Robotics project, but the code you write for that will be pure C#.
Understanding that, when I did start writing the script for it, the Script does not accept OneNote libraries to be able to connect to the functions. And I get this error as attached in the image. It doesn't work even when I select the .dll file for OneNote from Toolbox>Choose Items...>Pega Robotics Static Members>Microsoft.Office.Interop.OneNote.dll. Not sure if we can connect the Script to the .dll file to clear this error.
Is there a different way this is possible? Or am I doing anything wrong here?