I normally agree tha templates are for NPC, but in THIS case: Cyclic Reincarnation
the spell explicitly says that a non-humanoid creature (example: aasimar, tiefling) can gain (75% chance) the Young Template when returns to live.
Example: Bob, an adult tiefling PC dies and is returned to live by Cyclic Incarnation in a young tieling; he is an adult in a young body.
By RAW, it must be used the Young Template, I am correct?