RAT 5, I’m so glad you brought up the cliche about it being a new a/c, with regard to any glitches with equipment. To this I would add that Airbus a/c from the A320 onwards require a higher dependence on instruments than others and crew are trained accordingly.
The Jepp app charts for Mumbai have a caution clearly marked for rwy 09: “Do not mistake Mumbai (Juhu) for Mumbai (Chhatrapati Shivaji Intl.)” and so as you said, this would, we assume, be in their approach briefing. Then why the deviation to the left of their original app track?
There’s much to be desired in terms of what happened on the first approach attempt.