Lol if your Account would not have been created in 2017 I would devinitely assume this is my fake-account to again bring up this topic xD
I do have the same need/issue. I think CloudFlare does not offer anything like this, even if it would be very easy, as you can easily check if both domains are really pointing to the same site (even if in a different language).
But they dont do this as far as I know.
Thats the reason why I still use Free-Plan, but its for me just not worth it to may 3 times 20€/month for something I just think is cool.
This way they actually dont even get the 20€/month from me… sad but thats the truth. Would definitely spend the 20€/month on them as I like CloudFlare.
Feel free to vote for the FeatureRequest (@sandro already linked it)
Also: with this Feature, new cool features could be applied.
Like on the .de domain preffering delivering from germany. on .com (gTLD) globaly. on .ch from switzerland and on .it from italy. Maybe with a higher package these setting could even manually be set.
But this would be a whole other Feature Request and no Feature-Request in this Forum will make it