Hi,
I do not recommend doing that. Those variables are made for internal development, not for personal customization. You would need an access to our CSS framework to do that, which is actually a private repository. So…
I would suggest picking up the sub-theme that best fit your needs from the Design Extras add-on, then create a Custom WP Plugin (or load a CSS stylesheet from your theme functions.php file, since color changes are more a theme-related feature), and write some simple CSS rules from there. I would also accept a request to create a new Design Extras color scheme if needed, but I don’t recommend creating a sub-theme, especially if it’s only to change some colors. It could be hard to maintain for you when we add new components (in that case, you’ll get graphic issues).
Best regards.