Hi I bought gsx yesterday using it for p3d v3, I tried to use the fix you posted but nothing changed
If your problem is the same as the OP, which is the Simconnect_text() missing error, I can only repeat and confirm it's caused by another addon which, using the outdated Simconnect from the original FSX (not the SP2), which doesn't include that API call (which was added in FSX SP1), has forced the sim to be stuck using this outdated version.
Everybody that encountered it so far, as fixed as suggested in that thread.
You might also try installing the Simconnect SP2 runtime manually (which is obviously done automatically by the GSX installer, but it doesn't hurt trying), from this folder:
\Lockheed Martin\Prepar3D v2\redist\Interface\FSX-SP2-XPACK\retail\lib\SimConnect.MSI
If still doesn't work, and you are still getting the same message about Simconnect_text(), which is the message this thread is about, than go back to the solution proposed in that thread.