Why does Gamzee's chronology make no sense?
It makes perfect sense. He goes through the timeline normally then he either gets dumped in Earth’s ocean and waits millennial or is sucked into the Black Hole that Lord Jack’s head imploded into. Either way he ends up way in the future on Earth where he sets up the Cali twins’ living quarters. Then he enters with Caliborn and just chills with him.
Pre-retcon Gamzee did jump forward in timeline to create the Alpha kids’ sprites and enjoy some Trickster revelry though.