I'm passing this request along:
To the devs and volunteer coders: Please see this snippet that uses mediawiki functions:: https://en.wikipedia.org/wiki/User:Dank/wishywashy.js
If you add that to your .js file on en.wp, then every occurrence of wishy or washy will appear in bold for you ... and if you hover over the bolded word, you'll get some helpful advice. People would like for me to automate some of my copyediting advice using this script, but highlightText, as coded in Mediawiki, won't even let me search for a two-word phrase. Ideally, I'd like to have arguments that are regex searches (or the lua equivalent), but at a minimum, I need to search for letters, numbers, spaces and punctuation, if I'm going to be using highlightText. (If your solution allows something like regex, I only need highlighting for the initial phrase that appears before any special regex functions.)
Being able to highlight two words seems like a very useful feature. I've already got ideas about how I might use this if it were possible.