As discussed so many times in the forum, all the latest liveries are included in the GSX full installer OR in the vehicle update installers.
As an *exception* to this, ONLY because we are still beta testing the latest version of Couatl/GSX, the full GSX installer hasn't been updated with SOME additional liveries that were added during the beta period. This means, while we are in Beta, in order to get all the latest liveries, you must download the more recent vehicle updates installers.
After the beta period is ended, we'll be back to normal, and we'll revert to the usual system that, all the current liveries will always be included in the current GSX full installer, and the separate vehicles update installers will only be needed if you don't want to download the full installer again.