If a 767-300 has an L2 door before the wing, it’s normally the L2 door used, most of the British airlines who have operated 763s have gone for the configuration we get as player planes, British Airways, Thomas Cook, TUI etc. Every time I’ve flown on them they’ve used L2, be it on stairs or jetbridges.
I think with the in game 763 though, the door configurations are possibly on the same layer as the windows and fuselage details, so they’ve been scripted to use the front and rear doors with L2 being cosmetic only and not functional.