Yes, if anyone took that to be God's only activity, then it would be severely limiting, and hardly almighty.
I do believe God exists apart from His creation (transcendence), and throughout it (immanence). I do not believe He is only transcendent. Does any Christian?
I don't know. I do know that most people believe what they want to be true, or what they've been told and never bothered to reconsider for themselves. I also know that conceiving of God as some human-like magical overlord leads to an irrational acceptance of unhealthy religiosity.
I can accept that "God" is a form of existential transcendence, but not without acknowledging that I can't possibly comprehend what that would actually mean.
Was I reflecting on His existence beyond (or behind) Creation in the OP? Definitely. But I don't think that's all He is. Neither my words nor my thoughts could encompass all that He is.
God is whatever God is regardless of what we think God is. And there isn't any way for us to know what that is, for sure.
I'm more interested in what we choose to think God is, and how that effects us. I am anti-religious, in general, for example, because I think most religions are not about God at all, but are instead about the ego; control, fear, and the desires of the adherents.
Can't I contemplate individual aspects of His nature anyway?
So long as we realize that our contemplations are speculative, and tell us more about ourselves than about "God".
I do enjoy that. And I enjoy discussing it. Is there anything you specifically disagree with in what I've said? I really do enjoy talking with others about these things.
Most people who "believe in God" don't realize that what they "believe in" is just their idea of God. What they are believing is that their idea of God, is God. And there is a great danger in this pretense: the arrogance and hubris of unquestioned self-righteousness. Which is a highly addictive drug for a significant number of people.
I don't object or disagree with your perspective experience of God. I'm just warning against the human propensity to confuse this perspective with the actual.
I'm not sure how you're using the word transcendence here. And I don't mean that as a criticism. What do you mean by transcendence in our physical universe?
An example would be the transcendency to matter from energy. And then the transcendency to life, from matter and energy. Or the transcendency to consciousness from life. In each instance, a whole new realm of being springs from within a previous realm, the possibility of which could not have been foreseen or anticipated.
Gestalt: where the whole is far greater in scope and effect than the sum of it's parts.