What are the chandelier cities hanging from? Really really low "orbital" rings in the deep atmosphere, not far above the mantle? Since anything higher up in the atmosphere would get smashed by the aliens. In which case the chandelier cities might instead be growing in every direction. I'd also move Mercury a few million km closer to the Sun so it's tidally locked and gets even more solar energy. And fix the weird elliptical orbit too. Maybe reduce the gravity a bit too to compensate for the slightly increased delta-v.