I'd say that the Aamaniians started switching to 'Aa'-based names a few generations after the Cult Wars ended. While it likely started prior to that among the faithful, it wasn't likely as...

It seem like sign language would be an inefficient use of their time. Their spoken language would probably take the two brains into account so that a single sentence would have two different meaning...

There will be but it will happen around the time the book is available Although I?m dying for it to be seen now.