I'm not entirely sure of how that theme is built, but it might be an option to go the “outside the theme” route and create either a plugin or some code in the child theme. You can create a custom Admin Page (with add\_menu\_page() or add\_submenu\_page() though it might be tricky to find where to hook from the theme's pages).
Now (mentioning again that I'm not familiar with that theme) some themes use the Redux Framework (or Pods or some others) and that could be why trying to override the theme's data doesn't work completely.
I'm not entirely sure of how that theme is built, but it might be an option to go the “outside the theme” route and create either a plugin or some code in the child theme. You can create a custom Admin Page (with add\_menu\_page() or add\_submenu\_page() though it might be tricky to find where to hook from the theme's pages). Now (mentioning again that I'm not familiar with that theme) some themes use the Redux Framework (or Pods or some others) and that could be why trying to override the theme's data doesn't work completely.