All Christians are in heaven...But no one knows besides God who the real Christian is...Just because someone stuck the name of Saint on someone in your religion doesn't mean the 'Saint' actually made it to heaven...
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.