Since angels are ethereal beings, made of spirit, but can take any form to do the will of God, we cannot TRULY understand them, being that we are confined by our createdness.
SO the very idea that we are putting human qualities like learning and understanding to angels, is problematic.
If an angel can purposefully rebel against God and His will (Lucifer), then I would bet that they can learn about us and etc.
What their role is in our lives is completely up to God, so if they are learning about us it is because God wants them to.
I have no idea if I answered your question. sorry...