Firstly you should state this properly, since you've already stated you're prone to becoming confused with ambiguous verbiology.
"Let's say that 100s of people throughout the world are asking Saint Y to intercede on their behalf. How does Saint Y know of all these petition".
We know from the Bible that the Saints are in heaven and Praying, and that their Prayers can intercede on our behalf. It's plain in the Book of Revelation as well (though you mentioned you don't find the Book of Revelation to be authentic).
Regarding the Book of Revelation, you clearly have me confused with a different poster.
Let's say millions.
How does St Y know about all of those?