Regarding types check out https://eno-lang.org/javascript/#loaders - basically eno allows arbitrary types on the language level and provides loaders for all primitive types and currently also a small set of non-primitive types through the libraries. The extent of loaders provided out of the box might grow, likely also externalized into companion packages like https://github.com/eno-lang/enojs-exploaders/, which currently serves as experimentation ground for this.

The core might in fact be reimplemented in C or Rust and used across implementations through native bindings, although only a small portion of the actual parsing core can actually be outsourced like that, so it will depend what the actual benchmarks say then, there's also cost associated with passing around the data through bindings, the devil's in the details there unfortunately. :)

The editor in the introspection demo is atom, the introspection is based on the excellent automcomplete boilerplate at https://codersblock.com/blog/creating-an-autocomplete-plug-i... paired with a few lines that utilize https://eno-lang.org/javascript/#Section-lookup to determine the exact context for the autocomplete suggestions. Glad you like, thanks for your interest!