This is about how each character adapts to the radius, not the path itself. Each character is tweaked so the design holds up as it’s curved. I don’t think you have tools to do that.
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.