I can only repeat and confirm there never was "parking brake error" with the FBW A320 to begin with, since support for the custom parking brake variable used by the FBW A320 has always been there since the release, and nothing has changed.
Of course, I assume you are using the default configuration that comes with GSX, which you can verify by checking the airplane editor is using the internal data, not a custom profile which might not be correct.
