Construct is primarily a game engine so there hasn't been much of a push for features related to "creatives" even though it beats just about all existing frameworks made for ads already... except a few features like the one you are asking about.
That being said it should be possible to embed the uri strings into variables, or other means, but you have to take size into consideration.
Svg might be a better approach, but that file type hasn't really gotten the attention it deserves in Construct. To be honest adding some things is often easier said than done.
Then you still have to get the runtime embedded into the html file.
That would require a fair amount of elbow twisting of the developers.
Any way I am curious as to how well this has worked out so far.
Sharing your success stories might actually grease the wheels for adding these things as well.