If I may, I’d like to offer a few thoughts. I had a period of my life where my initial Calvinism, which was fairly wooden, was profoundly challenged. But for myself, though rough edges were removed, in my later years my confidence in the sovereignty of God, including His sovereignty over salvation and the fallible human will, has only increased.
For example, I notice you are using the temporal escape from the root problem of fallen human nature. No Calvinist worth his salt speaks of man’s will not being free. God does not compel us to choose against our own salvation. We do that to ourselves quite handily. The real problem, which putting God outside of time does not resolve, is the genesis of saving faith. Does it arise ex nihilo, without any aid from God? That is Pelagianism. Does it arise in all hearts by the mercy of God, only to be lost in some by the rejection of grace? Then it was not saving faith, and the problem remains unresolved.
You see, one of the problems of greater age is you begin to realize the profound truth of that Scripture which speaks of how, apart from miracle, the leopard does not change its spots, nor the Ethiopian his skin. At a certain age, you finally accept that what a person has done the will always do, for good or evil. Except sometimes there are miracles of change, from death to life, from darkness to light, and they always, always bear the fingerprint of God.
Indeed, it was the acceptance of this tendency of humans to remain bound by the inertia of evil that inspired the elaborate checks and balances of our Constitutional system. What Marx rejected, even more than capitalism, was the Calvinist belief that our sin nature cannot be cured by mere reprogramming of the human heart. The reeducation camps, the brainwashing exercises, the gulags and the populating of mental hospitals with political prisoners, the rise of the so-called therapeutic state, are all failed attempts to edit human nature into some soulless state of perfection, and of course they must fail, because only God can grant a lost soul saving faith and the changed nature that follows such a faith as sure as day follows night.
Which is why, although I respect the difficulties sometimes incurred by holding such a belief, I continue on with it. As you say, God does speak truth to us, and He has spoken truly about the need for His intervention in saving lost souls. That does not mean I am always ready to hear His message, or hear it accurately. Jesus held the Pharisees accountable for the truth He told them, even though they managed to hear it completely upside down. But as it says in Hebrews 10:39:
“But we are not of them who draw back unto perdition; but of them that believe to the saving of the soul.”
God must intervene to provide means of salvation, and the savee must decide to accept the means. Having the individual causational (and provisional) vectors of that action be perpendicular to the time line known by man solves many philosophical questions. Fancy labels (this-ism, that-ism) don’t negate the basic truth that you can be offered something and refuse. Until accepted the Holy Spirit can’t save, He can only invite and warn. Preserving an accepted salvation to the end of physical time is a no brainer, intellectually. Spiritually it was an astounding burden for God.