I figured out the problem! Before I start, I want to note that this is the first time I've relied on files that I didn't have a local copy of while programming. I assume this concept is probably well understood by people with more experience, and I provide the below "obvious" explanation for fellow newbies like me that may come across this:
It turns out, GitHub updates certain things (such as the raw files for apps to use) at specific intervals (maybe every five minutes?), which makes sense in retrospect.
My subfolders could not be found because, even though the ability to view them on a web page was available immediately, I still needed to wait until the app was able to access them.
The same issue can also pop up when updating a file on GitHub. I figured it out when I discovered that I had to wait a few minutes before an error I fixed finally went away.
Bill: What I did was create a public repository, chose "create new file" in the repository, and directly pasted a bunch of code that I'd previously had in shared scripts. I named the file
- [Category_Name]/[Library_Name]/[Descriptive_Name].js
This created both my subfolders and the files.
Side note, there are definitely other ways to do this that tend to be vastly preferred, but with the way MD is set up (combined with me pretty much exclusively using the phone app rather than desktop), I've decided that this roundabout, amateurish method is good enough.
To add it to MD, choose "Add GitHub Repository," and then, if you copy the URL for the subfolder directly from the address bar, you'll get (assuming you used the same naming structure I did):
just erase "/tree/main" from the URL to get
And use that URL to access the repository.
As a side note, it's possible that functions you want to use in JavaScript fields need to be in files that are separate from the functions used in shared/trigger/action scripts, but it's entirely possible that I also only ran into a problem with this because I tried to use the "fixed" file before GitHub updated the raw file. I think I actually prefer to keep them separated, so I'm not inclined to put it back just to check.
(Sorry for not having a German translation. Unfortunately, I'd be restricted to using Google Translate, and I have a feeling that your own translation abilities are much more accurate than that of a machine's!)