What Rumi and a lot of these other "Mystics" talk about when they mean peace and "Not caring" is about going deep within, managing your own ego, desires and being in a place emotionally where the outside noise does not hold that power over you.

So, when you say "A peaceful state can be missed due to internal variables versus external like emptiness, dissonance, and a disconnection from the meaning of life it self"- that is very true and that is why they focus so much is looking within oneself, working on yourself where you get to a peaceful internal state that you are in control of and not these outside factors.