It's not completely clear to me where in the mpackage zip it belongs. Must it be in the root of the zip, or can it be anywhere? How does "automatically" identify font files in either case? If it is not automatically made available, what debugging steps are recommended?To install a new font with your package, include the font file in your zip/mpackage and it'll be automatically installed for you.
Is there a way to load a specific font file from a specific location outside of this process? A common font license forbids distributing fonts directly but does allow downloading them, but it seems like this automatic process precludes that entirely.