I'd like to display some information on the author, as opposed to the respective author's archives.
In order to do this at WordPress.com, it would need to be built into the theme and The Columnist theme does not have an author page built in.
Twenty Thirteen is one example of a theme that does include author information from the Users > My Profile page, but (like most themes) only includes the "About you" description:
I also know that for wordpress.org you need to edit the author.php template, but that's not possible for wordpress.com. That being said, is there any way I can edit the author page? Perhaps with CSS codes?
There isn't. An author page isn't included for The Columnist theme, and CSS is only for changing the appearance of elements that already exist on a page. CSS cannot add a new page or new functions.
If you wanted to get complete control over the code or be able to add your own author.php page, moving to a WordPress.org setup would be the way to do it. See this page for more info if you're interested: