I'm not sure if the author meant current versions of emacs (with their 42 year lineage) or not. But if that's the case, then I think emacs was one of the very first to support Unicode and whole different scripts. If my memory does not fail me, emacs had extensive wide character support long before Unicode. With an extraordinarily broad treasure trope of different input methods on top.

emacs has also always been (in)famous for its text update render algorithms, that probably still work well over the old slow terminal lines it was originally used for.