Your final objection appears in the third paragraph, p. 143: “There is a subtle point here that is easy to miss, and yet I do not see a way around it.”
Regarding Kant’s distinction between existence as a property and instantiation, p. 123.
Regarding your objection to Kant about existence versus necessary existence, p. 127.

On p. 143 that is not what I wrote. I challenged the very assumption that one can conceive of it as existing, and I emphasized that according to the fool the difficulty is even greater.
On p. 123 I bring Kant’s distinction, which says that the instantiation of a thing is not one of its predicates. What you cited is Anselm’s argument and has nothing to do with Kant. In any case, I don’t see any connection to the rejection mentioned above.
And on p. 127 I added that the necessity of existence may indeed be a predicate, unlike existence itself. Again, I don’t see any connection to the rejection mentioned above.

Indeed, I’m asking in light of the fact that you challenged Kant’s words (p. 127). So we are left with the only objection that, from your perspective, remains valid — the one on p. 143.
That objection attacks what Anselm presents, namely that it can be conceived.
But it does not hold against the proof that God is perfect and that one of the perfect properties is necessary existence (p. 127), and therefore He exists.

I don’t understand the question. Please formulate it clearly here.

As I understand it, there are two ontological proofs for God that are seemingly identical —
Anselm’s proof about the greatest being that can be conceived.
And Descartes’ proof about the most perfect being.

When you claim that the fool cannot conceive of God, you are attacking Anselm’s proof.
But Descartes’ proof remains, because it does not speak about our cognitive ability, but about the very definition of the concept — the most perfect being.
There it is customary to argue, following Kant, that existence is not a property (a perfection) but the placing of the concept in reality. But you argue against him that he is right only regarding contingent beings, whereas with regard to a necessary being this does not apply, because necessity of existence already entails “different” properties.
So why do you reject the claim that God is the most perfect being — necessary existence is more perfect than a being that merely exists, and from this it follows that He exists.

First of all, I dealt with Anselm’s formulation, not Descartes’. Anselm is more precise, and I explained this throughout the discussion.
Beyond that, existence is not a property; its necessity is a property. Therefore, even in a necessary being, existence is not a property.
Bottom line, my main claim was that the argument is not ontological. The question whether its conclusion is correct or not — of course it is correct. As for whether the argument, once the additional assumptions are supplied, is valid — definitely yes. But one may dispute the additional assumptions that I spelled out along the way.

Interesting — you’re saying that even if necessity is a property, existence and the instantiation of the concept are not connected to the argument.
For example, can one say that “God does not exist” is contradictory, but only on the conceptual plane and not on the objective one?

If He exists, then it is necessarily so. But it is still possible that He does not exist (because existence is not a property/predicate). Therefore, to say that He exists non-necessarily is contradictory, but to say that He does not exist involves no contradiction.