Josie I must say I admire the energy and perspicacious CCC research you are putting into this.
Just a few minor misunderstandings have tangled you a little…
So why do you say any sin (even non imputable deeds) may or may not be of grave matter, or a sin at all? It is like you are saying there is a third type of sin.
Can you quote me where I allegedly said this? I simply stated that misdeeds of grave matter are regularly enough actually only venial before God, and sometimes not even true sin at all. We called these “sins” transgressions or “material sin”. To be true sin they must be “formal sin” of which there are two types, venial and mortal as you state.
Aquinas states that the only real sin is mortal. We call other things “sin” only by analogy (ie a weak likeness that leads to real sin). This list of weaker offenses we commonly call"sin" in order of lessening malice are: venial sin, original sin, state-of-sin, transgressions, imperfections, concupiscence. We might quibble over the ordering.
We cannot love God if we sin gravely against him, against our neighbor or against ourselves.
Be careful not to confuse “sinning gravely” with “Grave Matter”. The former is ambiguous, though usually it means mortal sinning. The latter is a highly specialized technical term.
It simply refers to one component of a complete human act. The complete act may or may not be truly sinful. You would not be wrong to call grave matter any disordered action. And of course disordered actions by themselves are not enough to define sin in the fullest sense of the word. We need to know intention and circumstances and levels of coercion and levels of gravity etc before inferring the presence or mortal sin, venial sin, mere transgression or imperfection…
This is the CCC article that briefly makes my point:
1735 Imputability and responsibility for an action can be diminished or even nullified by ignorance, inadvertence, duress, fear, habit, inordinate attachments, and other psychological or social factors.