The very existence of desire indicates a lack of satisfaction.
Maybe that is a large part of the problem of terminology, and gets us into the "confident expectation" material.
If I am happy and healthy now, I still want to "desire" that to continue. I am never satisfied to think "Ah, I am happy now, I need nothing more, time to die." I always want ("desire")the continuation of pleasure, even though I know that in the end I will die and I will experience no more. Even when i am closed to my experience being full of pleasure and all pain being absent, I still want that experience to continue.
Possibly we need to go back to the physics for help here. It has seemed to me in the past that the key to proper interpretation of many aspects of the philosophy is that nothing is ever truly "at rest" -- our atoms are constantly moving, our bodies and minds are constantly functioning, and they never stop until we die. That observation is also helpful in seeing the limits of "tranquility" - we're never really at rest. We may wish our sailing to be smooth and undisturbed, but the analogy of sitting at anchor in a harbor in perpetuity "is not what ships are for."
We at the very least desire this motion to continue, and we cannot ever say "I have reached a state of motion that I find perfect and therefore I will freeze everything in place." That is not possible, nor a conceptually sound way to look at life, I would have to think.
So I don't know that the "very existence of desire" in the most general sense indicates a lack of satisfaction, unless you want to say that you should be satisfied where you are at a particular moment and then stop all the activities of life and die.
So maybe I would argue that the existence of desire indicates that you are alive - not that you are in a state of frustration.
I can certainly see that the desire to stay alive runs into the knowledge that we can't do that perpetually, but when you drill down that level I think you're at the point of the cliche of "making the perfect the enemy of the good."
Perfection (eternal life) is not possible to us, but that does not mean that we consider life, and the desire for its continuance through an natural lifespan, to itself be a frustration. Does it?