@johan_m_o - for external modules like this referenced by URLS the App loader pulls in the code when you install the app. During development you will have to have the code loaded into the RHS window of the IDE and upload to Storage by setting the appropriate filename.
Personally I prefer actual modules in the app loader / Bangle Codebase. I would always worry that the code would dissapper from the remote URL.
See my Pastel Clock for an example of how I use an external refernce for sunrise/sunset calculation and local modules for fonts. I just wanted to keep the amount of code low in my main app.
Yes, I've seen those examples. But, when is the download supposed to take place? Does that happen when the app is uploaded to the watch?