I get that part (I've designed commercial typefaces), but as I understand it, (1) this only works for type on circles or circular arcs, and (2) the typeface has no awareness of the circle/segment it's on, so the designer still has to manually match the Curve property to the radius.

I think this is really cool and interesting work by Nick Sherman. I just wonder if I'm correct about the limited applications, and what could be done to enable the kind of "contextual intelligence" that would enable fonts to better optimize themselves for a broader set of types of envelope deformations.