You miss the point:
Sinners damn themselves; heretics damn thousands.
Heretics don’t damn anyone.
They may teach what the Catholic church calls false teaching, but nobody is making anyone else believe it.
People choose to believe what they want. Nobody forces them to believe it.
And besides, doesn’t the CCC make exception for being invincibly ignorant? If they don’t know they’re being deceived and are sincere, that covers them, right?