Thanks for updating the thread.
It's difficult for us to give you the assurance as update process depends on lot of factors for ex hosting infrastructure, website architecture, level of customisation etc etc. That's the reason why I suggested you to test the update on a staging server.
As you said that the article were not made using Cornerstone, does that mean you haven't used Cornerstone to create any content on the website? If yes, then I don't think there should be any issues while updating. However, I would still suggest you to test on a staging server.
Unfortunately beyond this it will be difficult for us to provide support. I think we have provided you all the necessary information that's required to update Cornerstone. Now, it's on you to take a decision.
Thanks for understanding.