Itix: ... there's no such thing as OS support for Arexx.. Never has been.. Arexx is indepemndent 3rd party program that Commodore just happened to License in their further versions..
I do have original Arexx, which I purcased directly from autor (Will Hawes IIRC?) well before Commodore used it on their OS:
Besides.. Arexx-port is totally program dependant feature, and there definitely were a considerable number of programs with Arexx port well before 1.4Alpha (later to be released as 2.0)...