You are doing a lot of unnecessary steps. The main problem is caused by CS having the habit to have almost identical variant of each airplane in a separate folder, even when it's not really required. This means, even if GSX supports the airplane internally, it only supports one variant.
The easiest way to make it work is:
- Load a variant that is not recognized, and open the GSX Aircraft configuration page.
- Edit anything, doesn't matter what, even clicking/unclicking an option it's enough.
- Click the Save button, so GSX will create the proper folder name for that variant with a new GSX.CFG in it.
Copy a GSX.CFG from a RECOGNIZED variant over the new folder and overwrite the one that has just been created with this process. If you don't have a folder with a GSX.CFG for a RECOGNIZED variant, just make one, using the same method as above, load it, edit it and change something, so the custom folder with a GSX.CFG will be created in %APPDATA%
The recognized variants are those found in these folders (under Simobjects\Airplanes )
CS_B777-200
CS_B777-PAX
CS_B777-200ER_GE
CS_B777-200ER_PW
CS_B777-200ER_RR
CS_B777-200LR
CS_B777-200ER
They all use the same internal config as the CS_B777-200 because, as far as GSX is concerned (measurements), they are the same airplane. If you have a new variant which comes in a folder other then these ones, you must follow this procedure, to copy the config from a recognized variant.
Doing a config for the Freighter will be more involved, since the config copied from a passengers version will surely have to be edited (but it can be a reasonable starting point) to match the different doors configuration, flag the airplane as cargo, set the correct XML expressions for the Main Cargo door, etc.