This morning I upgraded my system to Windows 10. Following that, Couatl no longer starts up in P3D.
Your screenshot clearly indicates that Couatl IS starting correctly. If it didn't start, it wouldn't been able to gave you an error log to begin with.
From your error log:
couatl v3.1 (build 3487)
NameError: global name 'getAvatarId' is not defined
It shows you have an outdated version of the program, because you haven't updated the Stand-Alone Addon Manager, as request by the last Live Update notification, that maybe you must have ignored.