I have never used Unity, so I don't really know how well-suited it is for your goal. However, I have the very strong feeling that it would be massively overkill and probably hinder you more than support you. I looked at screenshots of WMMA ... like you said, it's really mostly text. The most important thing you need for this is a good layout engine that allows you to create stuff like tables, lists and tabbed panels easily, and ideally also make them look somewhat nice.
The first, natural choice for such a thing would be HTML+CSS, i.e. a web browser. It doesn't even need to be fully web-based in the sense of having a client/server architecture. Take a look at Electron. That's a framework/engine based on Google Chrome to build desktop applications with web technologies. Your application window would be a Chrome viewport displaying a HTML document that represents your UI, but without the URL bar, menus and other browser UI elements. In the background, you'd have a JavaScript program that processes all input, manipulates the HTML/CSS output and also, unlike a normal browser, has full access to the file system and other local resources. I think this would be my first approach to such a thing. And, if you don't like Javascript, like me, you can of course also use TypeScript (a million times better).
[edit:]
I just saw that Electron is also based on a client/server architecture, but my point is still valid in the sense that you have everything in one package, to easily install and run all on the local machine. From the end user's point of view, it feels like a normal desktop application. Visual Studio Code is a famous example for an Electron-based application, and it does in no way feel like a web app at all, except for the funny and interesting fact that you can open the Chrome developer toolbar and examine the HTML/CSS/JS that defines the UI and see that it is really web-based ;).
