Dynamically typed languages are far from "untyped". Though they may well require more effort to analyze from scratch without making assumptions, there is nothing inherently preventing type-constrained code generation of the kind the first paper proposes even without static typing.

A system doing type-constrained code-generation can certainly implement its own static type system by tracking a type for variables it uses and ensuring those constraints are maintained without actually emitting the type checks and annotations.

Similarly, static analyzers can be - and have been - applied to dynamically typed languages, though if these projects have been written using typical patterns of dynamic languages the types can get very complex, so this tends to work best with code-bases written for it.