I believe it's in developers' hands to better handle their image assets in their apps so that iOS recognizes what to and what not to invert. For example, in games like Clash of Clans, perhaps the whole UI could be declared as an image class media, allowing one to play without hassle.
As for websites, Apple should work safari so that if the background if a website is set to a defined range of bright colors, they must be inverted, as must the text. I have a feeling this won't play well with frameworks such as materialize or bootstrap because of their priorities set extremely high.
I think it's wishful thinking that they'll improve smart invert in upcoming betas, I believe this is it. Apple clearly doesn't listen to requests and they pretty much ignored the iPhone this year. Maybe next year will when they pay attention to the iPhone os again.