Why aren't my base styles updating in the preview?
If you're removing styling from a base style, those styles still apply until you have saved the base style.
Acquia Cohesion renames to Site Studio from version 6.2. Tell me more.
Base styles are CSS styles for HTML elements.
No, there is no way to roll back an Acquia Cohesion package import.
With Acquia Cohesion Sync you can export Acquia Cohesion configuration in full or in part as a package that can be imported into a different website.
An Acquia Cohesion Package file is a .yml file that contains Acquia Cohesion Configuration. The package file allows you to import and export between environments.