2 Weeks any update on the issue?
I already replied to you by email, you must have missed it or it might have been lost for some reason (anti-spam, maybe).
In my email reply, I said there wasn't anything wrong in your install.log, GSX correctly detected FSX:SE in the correct folder and installed everything correctly.
The problem, is that *FSX:SE* is instead looking in the wrong folder for the DLL.XML files, most likely because it BELIEVES you still FSX installed, this likely because you HAD FSX installed before, then you removed it without reinstalling FSX:SE and you haven't removed it entirely, the same problem happened here:
http://www.fsdreamteam.com/forum/index.php/topic,13998.msg105830.html#msg105830To fix this, edit the following registry key using REGEDIT:
HKEY_CURRENT_USER\Software\Microsoft\Microsoft Games\Flight Simulator - Steam Edition
Change the value of the Registry Key named Co-existence from 1 to 0
Start FSX:SE and it should probably work now.