I repeat and confirm again: there's NOTHING wrong in your XML file, your Trust section, your FSX.CFG, your antivirus config, your Windows config, and everything that has been discussed here.
ALL these troubleshooting solutions are only meaningful for user that DO NOT see either the Addon Manager menu or the Couatl menu, or both. If you see both menus, there's just nothing to be done, everything is working correctly and none of the suggestions are relevant to you, because the programs are both running fine.
Things that might prevent buildings to display, even with programs running, are:
- A Couatl module had an error. But you said you don't have any couatl.err file in %APPDATA%\Virtuali so, this is not the case
- You moved the sceneries from the default folder, this might prevent the Addon Manager installer to find and install updates for the sceneries, if needed.
- You are using a very old version of the sceneries. Have you tried with their current installer ?
- You have your Scenery Density slider too low. I think that it has to be at least at Normal.