But if someone dies a Christian according to you, they are in Heaven. Therefore whether that person has a title of “Saint” is irrelevant. If that person died a Christian then he/she is in Heaven and one can know who they are praying to for intercession. You said that a person could not know who was in Heaven.
Let's not make this too complicated...Only God and the person God deemed to be a real Christian is in heaven...Regardless of what one claims on earth, only God and the Christian knows the Christian is in heaven...
The best we can do is hope the person who claimed to be a Christian on earth had a real heart change to become a real Christian...None of us knows for certain what our friends and relatives or pastors or popes or Saints had in their hearts...
Therefore, the only one we know for certain is in heaven is God...He's the one we need to pray to...