I also forgot to mention that maybe if you created separate installers, one for fsx and one for p3d, might solve several issues. It seems to me that since P3DV4 there have been numerous problems regarding installs. Not knocking your work, just a suggestion.
The installers are not the problem and it won't be different at all, even if we had an useless separate installer for each sim. We didn't had any problems with the installers, only users that don't understand the new installation method (which is the one suggested by LM), and ASSUMED they had a problem, even if they didn't.
And some bugs in V4, like the one where a corrupted EXE.XML caused by a flawed beta UT2 installer, caused ALL the other executables (not just ours...) to stop being loaded.
Your problem, which right now only you are reporting it, clearly indicates the software is working, otherwise you wouldn't see all the other FSDT sceneries. Your problem is ONLY that you are still getting an outdated .dat file, while the correct one is online so, your issue doesn't have ANYTHING to do with the software modules, but it's ONLY a Live Update issue.
The Live Update obviously work but, in order to make it as fast and reliable as possible, we run over a CDN network on top of Amazon, with multiple servers spread around the word, so users won't get the same files at the same time, so I believe you might getting the wrong file.
To verify this theory, try these links:
http://update.fsdreamteam.com/setup/fsdtroot/bglmanx_fsdt.dathttp://update.fsdreamteam.com.s3.amazonaws.com/setup/fsdtroot/bglmanx_fsdt.datTry the first link, and put it in the Addon Manager root folder. If that doesn't work, try the 2nd link. They are supposed to be exactly the same file, and they ARE but, if the first doesn't work for you, and the 2nd does, it means the problem was the Cloudflare node closer to your location, which still hasn't got the latest file.