For normal humanoid spellcasters who have to prepare and channel the spell energy that is foreign to them through their bodies, being such a strong spell it always carries the risk of backfiring going beyond the predetermined rules of its preparation.

nothing to say that is the case for dragons who can cast the spells innately.

Good thing you can cast Simulacrum first, then use the simulacra to cast wish

However, the spell replication is already extremely powerful.