Virtuali, I did run that test with no external addons and default trike, and got a successful exit
This clearly proves the problem wasn't anything in our programs.
which is why I went ahead and performed the test one addon at a time and still failed to reproduce the problem.
This seems to indicate there's not a specific problem between Couatl.exe and another specific addon module.
It's only when running all the addons together that I experience the problem, however trying to narrow down exactly which addons are minimally required to cause the fault is a combinatorially hard problem.
This should be easy to test, instead.
You said you enabled all addons, one by one, but if you enabled them one by one, with each addon singularly enabled, this won't catch the combination issues, that's why you weren't able to reproduce the problem,
What you should do, instead, is to enable all add-ons, one by one, but keeping the previously tested add-on ENABLED, so you are progressively increase the number of modules loaded. This way, it should be fairly easy to catch WHEN the conflict happens.
EDIT: Also, when I tried installing the 2.12.15 update to the SA Addon Manager, couatl.exe was running from the previous FSX session, and the installer failed to close it; I had to override via Task Manager.
That's normal. The installer checks for it, and it tries to close, but it not always succeed.