As you may have seen, I recently posted another question/problem relating to paper vouchers. But in the process, I have asked the question you posed a few times to AA agents. The answers I have received have varied from "it should take a week or two" to "we process them in the order received" to "it should happen next month" to "it can take a couple of months" to "I don't know; I don't work in that department."
The lesson I have learned from this experience is that I should have gone to the airport and redeemed the vouchers in person.
One of these days, AA will enter the 21st century and switch entirely to electronic vouchers. That would save us -- and I suspect them -- a lot of hassle. It is hard for me to imagine any advantage to paper vouchers, other than the possibility that revenues might be enhanced if they are lost or not used....