Just skimmed through your blog a little, I really appreciate that it exists and people are still putting effort into writing vs. everything streamable video and all the usual whatnot.
Fun fact I was one proxy away from finding your map, even though I had no idea WTF a Jewel was but that we were looking for its case (ba-dum-tss). Your thread made me start an EDuke bug report thread after I remembered I could no longer check a lot of shovelware-era user maps in current versions of the port (that's being looked into, unless it turns out the problem is on me), thread in which I uploaded the EXTMAP folder from the 'Come Get Some!' compilation (Softkey, 1997) as a sample for debugging purposes. Whilst at it I checked every .txt file attached to the maps in that folder in case I could find yours, and it actually was in there, and I even looked at it and read the thing. But it eluded me for the exact same reason as you, .txt file mentions absolutely nothing about the contents of the map

Glad you found it.
I read that you would be interested in fixing the bugs. I'm sure any competent mapper could clean those up in seconds, however I do appreciate that you are being considerate of the original author's intent. Could always track them down to find a possibly newer email, but that always comes with the catch of sounding like that guy, 'hey, remember the video game level you made for fun thirty years ago then completely moved on from, well I do and here are all of my questions about it'. If I were you I would just edit my local copy (or get it edited).
TBF one reason why I've been digging through those old shovelware folders lately (especially maps that came with custom .art) is I believe there would be something really cool to do in making modern versions of lots of them, using the original texture packs for each and just recycling the level concept/theme into new layouts that would be more of the time (for better and for worse), especially if there is contrast between .art quality and .map potentially could look pretty funny but hey the things one would do with unlimited time.