You can find within "Condemning The Errors Of Martin Luther", where Pope Leo X specifically points out one of Martin Luther's errors 33. That heretics be burned is against the will of the Spirit.
You can try and say that is was secular authorities that burned people at the stake, but the practice was approved and sanctioned by the Pope.
After Pope Leo X summarizes Martin Luther's errors, he concludes with this statement. No one of sound mind is ignorant how destructive, pernicious, scandalous, and seductive to pious and simple minds these various errors are,...
So that idea that it is wrong to burn people at the stake is harmful to pious and simple minds. Wow.
The death penalty is not intrinsically evil. The church has always taught that. Even now it is not intrinsically evil. So your post is correct...the Catholic Church did not condemn the practice of burning heretics.
Is your religion opposed to the death penalty?