You are correct and well learned; but I turn your attention to the part where you say It brings perfection and peace. At the same time you say it is unknowable. How do you reconcile these two statements from your studies? Either confess that you cannot know it; or say that it is knowable and you do know it. You speak from second-hand, therefore your knowledge is not your own.
Many are deluded on this point; and even the best learned will struggle with the reconciliation of these two points. It is grace alone that can reveal the truth of the matter of these seemingly paradoxical statements.
Consider a flashlight that wanders around aimlessly searching for the source of light. It goes on illuminating objects. Objects either conceptual or physical, are known by their qualities upon illumination. So the objects of illumination are the known. The flashlight is self-luminous so does not require to be illumined by an outside agent, therefore will always remain as the unknown. Do we say the flashlight does not exist?
Perfection is the illumination of objects without their conceptualization. Therefore, the One light of consciousness cannot be known but realized as the illuminator and not the illumined. Like the flashlight, it can only realize that it is the light and its search to know the source of light is impossible. It is It! Therefore, the Final Cause is always inferred by the fact of existence.
The Final Cause is realized as one’s self after turning inward away from the desire to have experiences in outside phenomenon (mainly the illumination of mind and body which creates an identification with them). This brings down grace which destroys the exclusive me. Once that occurs, then come back and meditate on that state and your doubts will be cleared.