No CE or its pre fates thats spawns in Bozja is random, they have triggers and there is a queue.

You can go in kill the mobs you need > your fate pops > kill it > no drop > jump out > retry.
You can kill the fate you want like twice an hour, the last one i needed was the cat with the unicorn which i had 50ish tries.

If you cant deal with the droprate of castrum and dalirada, theres the duels and dont tell me "well i never get in" notoriety helps you, the highest i ever got was notoriety 4 and that only happened once. Then its just "get gud" or "cheese it".

ALL southern frontline zones duels can be burned in 30-60sec by nearly all jobs.

Its an achievement, its not meant to be handed out free, grind for it ... or accept it and move on, there will be more mounts ... every single patch.
This is a lifeline for Bozja, to make players come back and while its prolly not needed right now it will keep players come back when bozja walks the way of eureka.