Yes. And no, I was able to scale to the highest resolution (3840x2160) without the cheat after a patch. I looked up the patcher you mentioned, turns out there's one for Legacy as well. My UI already looks like their improved one.
I googled the issue to see what people on Reddit and other Sims sites were saying. It looks like there is a split for some reason, between players whose UIs look fine and players who say theirs are too small or blurry. Other than individual computers, I'm not sure what would cause the difference.