The mobile stairs work perfectly, the problem only comes from the boarding bridges.
GSX doesn't have anything to do with jetways. How they work (or not) how they connect (or not) and to which door they connect (good or bad), is completely OUTSIDE any control by GSX. Jetways in MSFS are affected ONLY by:
- How the jetways are modeled (and in your case, you are reporting an issue with a jetway that comes with a scenery so, it's not even a GSX jetway)
- How the airplane is parked
- How the doors are configured in the airplane (NOT in GSX!!!)
No GSX profile is used for the aircraft.
This is clearly a mistake on your part. The DC Design Concorde is NOT included in the GSX internal database, so you MUST have a profile for it, either made by yourself, or by somebody else who shared it to download it. Without an airplane profile, an airplane that is not already internally supported by GSX simply won't work, at all.
You will also see the incorrect positioning of the Fuel Truck
Caused by the lack of a GSX profile for that aircraft.
and the GPU cable floating in the air.
That's a separate issue, we don't have a GPU with a cable long enough for a Concorde. We'll look into it, when FS Labs will release their own so, at least, the work to update the GPU would be worth for at least 2 airplanes.
Concerning the pushback, you will find attached the screen of the pushback in E20, on taxiway T43. The tractor completely exceeds the maximum turning angle of the plane, causing it to slide for several meters.
That's only because either the airport profile you are using doesn't provide for custom Pushbacks or, if it does, whoever made the profile made it for a smaller airplane and haven't tested it with a Concorde. However, your lack of an airplane profile will also affect this. All these kind of issues are always fixable by adapting a Custom Pushback to the parking, being sure the curve won't require such extreme steering.
Pushback problems also occur with other more classic aircraft (PMDG 737 / Fenix A320 etc.)
No, they don't, if the pushback procedure is programmed correctly.