Sundering Growth

You must target an artifact or enchantment to cast Sundering Growth. If that artifact or enchantment is an illegal target when Sundering Growth tries to resolve, it won't resolve and none of its effects will happen. You won't populate.

Any enters-the-battlefield abilities of the copied token will trigger when the new token enters the battlefield. Any "as [this creature] enters the battlefield" or "[this creature] enters the battlefield with" abilities of the copied token will also work.

Populate doesn't target the creature token you're copying. You choose that creature token as you're taking the populate action. You can choose any creature token you control. If a spell or ability causes you to create a creature token and then instructs you to populate, you may choose to copy the token you just created, or you may choose to copy another creature token you control.