A very good question, and you poke an open wound. Short answer is "No, but I seriously thought - and am thinking - about it and if I do it'll 99% be TypeScript-based."
The thought crossed my mind many times, while developing my biggest but unreleased DOpus script yet, a multi-threaded hasher; check my Github. That one grew to over 10k LOC/250KB at times, in 1(!) single file, which was frustrating to work with to no ends; now you know why the big figlets are there 
DOpus devs probably hadn't foreseen that user scripts might grow this large (I've seen a few other scripts in the forum upwards of 100-200KB) but neither had we foreseen that JS would rule all Internet 25 years ago. After the editor problem is now mostly solved, the single one "modern" (heh) JS feature I miss sorely in JScript is require/import/export or modularization, bar none. Shared, stable libraries with their own unit tests, etc. No other missing feature comes eeeeeven close. Unfortunately libs like requirejs.org don't help either, because the initial import is implicitly done by the browser runtime, which we don't have. It's remotely followed by missing for...of & the error handling in plain JavaScript, not just JScript but JS in general (see Type-safe Rust-like Result in VSCode for JScript and newer | cy-gh.github.io). I can either already implement or work around everything else: unit tests, enums, classes, inheritance, etc. Other missing syntactic sugar, promises, freeze, etc. don't bother me, at least not in the context of DOpus scripts.
The modularization problem put me on a crossroads and I froze all DOpus developments: Either I stay in WSH-land and use something like forum guru tbone's genius solution (HowTo: Create a function-library with Windows Script Components (WSC)) or switch to TS, which is obviously the "proper" choice. The problem is I don't use JS, TS, npm, grunt, etc. in my day job so many new tools mean a lot of learning curve and time investment, which I lack at the moment. Also my local, very ugly copy of the hasher script works very stable so the urgency to work on it mostly vanished. But at the same time that script also fundamentally changed my workflow and how I see checksums and file management. So I want everybody to be able to use checksums as seamlessly so I'll probably do it in upcoming months.
If you do any work on this, say prepare a small tutorial how to setup a small user script with TS/npm/babel/grunt backend, I'd volunteer to review/work on it together.