Why not continue what Johns did with Coast City as metaphor. Coast City may be back, but there's still lingering trauma and sadness about those who were killed. (think post 9/11 or Avengers: Endgame after the snap) It could be a recurring theme, giving Coast City its own characteristic and Star Sapphire having a unique hero/city dynamic where her role would be to ultimately help the city heal. (something befitting a hero whose powers are based on love)