Are you talking about Mozilla Rhino or the fork at
https://github.com/apigee/rhino?
I'm planning, in the next few weeks, to include the typed array support form Apigee Rhino to the Mozilla repo so that can be part of 1.8.0, and to a release out. (I need it for a project and I imagine that others do as well.)
When I do this, I'd like to make it possible to use typed arrays from Java code, so I'd like to change the Apigee implementation to make it usable from Java code as you suggest.
Does that make sense or are you asking about something else?