We cannot obviously reproduce this crash. We fixed several possible crashes, which could only happen when *exiting* the sim, because these were the only ones we could reproduce.
There's no way we were ever able to reproduce a crash while flying so, I believe that what you are seeing here, is not that Couatl.exe "caused" a crash but, instead, it's the opposite:
The sim itself, due to a combination of the memory-hungry airplane you probably use, too high graphic settings, too many addons installed at the same time, might have crashed itself, and the sudden crash bring down Couatl.exe with it, that couldn't do all the normal "cleanup" operation that are supposed to be made on closing, when the sim closes down cleanly.
So, it's not that Couatl is causing a crash. The sim, having crashed suddenly, has caused Couatl to crash.
Of course, a more precise indication of your configuration, especially the plane used, the other addons you installed, might help us identifying the real cause of the crash in FSX that caused Couatl.exe to crash too.