Just one correction:
If a URL is used in CSS to load anything, it’s not provided at the CDN level, necessarily. That URL is resolved by the client after the CSS is served by the CDN.
If the SVG is served over a path that is pulled from a URL through the CDN, only then is it “CDN’d”.
In your example, you’re using a relative path, which means it’s actually pulled from the local server, not over CDN. The client will look at this path as domain.com/imagepath, where domain.com is the physical location of your app server, not the remote CDN.
This is a common misconception that usually comes up when people are talking about GZIP; the idea being that a GZIP’d CSS file somehow has all linked and @import assets loaded as compressed items, too. Since those items are pulled in from files that are linked in the code resolved by the client, they aren’t necessarily GZIP compressed, unless their MIME type is set for GZIP on the server.
To really load your SVG assets over CDN, your background image URL needs to go over the CDN using an HTTP/HTTPS request.