When answering questions on this site with Mathematica code, Greek letters and special characters (which are valid in variable names in Mathematica) look like
\[Beta], for example. This can make the code harder to read and understand.
It turns out that the button I was asking for above has nothing to do with this site's management and depends only on a script that can be made to work on any of the StackExchange sites.
There are a few ways to turn such characters in more readable characters with that script.
0. Use a special website that does the conversion.
You can paste in text and all of the Mathematica codes (like
\[Alpha]) get converted. From that webpage: "Some of these are mapped to characters in the Unicode character set, and can therefore be translated into Unicode, suitable for displaying outside Mathematica. Others, however, are in the Unicode Private area, and are displayed correctly only using Mathematica fonts."
1. Install the script:
This gets you a button to convert such characters (selecting some text and then pressing the added button) but works currently only on Mathematica SE and Math SE (because those sites are specifically mentioned in the script and CrossValidated SE is not).
You can then go to a "Your Answer" box on those sites (Mathematica or Math SE), type in your answer for CrossValidated, and then copy-and-paste it into "Your Answer" box on CrossValidated. (Yes, that's not a very attractive approach.)
2. Modify the script yourself.
This (in my opinion) is not for the faint at heart. One can use a script editor such as Tampermonkey to add in the 1 line of necessary code to the above script:
// @include https://stats.stackexchange.com/*
(as discovered by @Scortchi-ReinstateMonica). I am not recommending or giving more details to this approach but only give it as a possible alternative.
3. Wait until the authors of the script add in the above line of code.
Then it will work on CrossValidated directly. (I have asked the authors and am awaiting a response.) If and when this happens, this will be the best alternative as it doesn't require installing things like Tampermonkey.