I tried to scroll through your video rapidly, because it was very long.
I think the problem with setting the height for the VGDS were caused by being close to the terminal, which in that scenery seems to have an intermediate floor, so the object is sensing it. We'll see if we could improve this, because to support sloped scenery, all object must be aware of the terrain, and this result in them being affected by it.
I guess we might try to improve on this, and switch to a different positioning ( from AGL to MSL ), the moment you start raising them.
About the missing Simbrief, I think the problem wasn't Simbrief ( and I confirm you GSX works on UTC ), but the fact the VGDS was blank. Normally, with the types with a screen, you are supposed to see an alternating message "On Chock / GATE XXX", even if there's nothing on Simbrief. The Docking system is supposed to be turned on either when you open the GSX menu with parking brakes on and engines off, or when you activate the editor.
If you want to check what Simbrief is doing, it's all logged in the Couatl.LOG file if you have logging enabled.
I noticed you struggled a bit with the Custom Pushback routes at Belfast.
I suggest reading Pages 40-42, which explain how the waypoints work. It might seem a bit counterintuitive at first, because most people think they are "just" waypoint, when in fact the proper word would have been "control point", not unlikely the ones used in Adobe Illustrator, where the final result is a smooth curve that passes through them.
Usually, the best workflow to create a custom pushback route is:
- Start by deciding the airplane final position and heading.
- Press NumPad 5, to obtain two waypoints that will be placed automatically in a way to ensure the tow truck will end up aligned with the airplane.
- Now you can add waypoints, playing with their position and heading, and see how the curve reacts, now it has been "pinned" down by the first two waypoint.