Sounds like the author wants his tools to be as fully featured as the code that will embody the resultant design. In that case I would recommend learning more code instead of relying on a proxy that will never be as flexible. The best designers I’ve worked with not only understand their own domain but the possibilities and limitations of how it will be executed, because they are also developers.
When someone says HTML & CSS is terrible I ask them to design something better that lets you represent user interfaces that can adapt across multiple screen sizes, and allow complex layouts that Flexbox and CSS Grid makes possible. It is easy to criticize something if you don't have to worry how you would do it better. That said, HTML & CSS is just how the world currently is. It doesn't mean that it is the best possi…
How about Cassowary, with size classes?
I spend half my programming time working on Mac software and half on web software, and I find element layout in the former is infinitely more pleasant. No need to put elements in a specific place in the document structure to lay them out the way I want. No need to change how I'm working for vertical versus horizontal layout. Just pick the dimension/coordinate you want to set, pick the other dimension/coordinate you want it to maintain its proportion to, and you're done.
Apple's implementation got a bad rap, I believe, because the first version of Xcode didn't support it well, the first version of the API was a terrible fit for Swift (which came a couple years after it), and pre-Sierra macOS had a lot of bugs in the implementation. Today, there's no layout system I'd rather use.