It is possible to have multiple A/AAAA records pointing to different loadbalancers, but I don't know how browsers would deal with this.
If there are errors, the site would need to be modified to not respond if broken and unable to proxy to a working origin. Perhaps CF have not coded their proxies in this manor.
But it does make it possible for a browser to retry a different IP if a 500 range error, or timeout occurs.
But like I said in my other post: I don't know if browsers actually do this.