Chronicles based on real history. However Trojan War is a legend. If they make another game mode like AoE 2 DE: Legends, they can add Amazons with Achaeans and Trojans.
As an UU, Amazon isn’t realistic too but it can fit Scythians. Scythians can be added to Chronicles. I think Scythian Amazon wouldn’t be less realistic than Saracen Memaluke or Malian Gbeto.