Has the fullness of Christ's divinity been revealed to men, or only "a small taste...at the Transfiguration"? Because it seems you're making a point of how the fullness of the Father's and the Spirit's nature hasn't been revealed to us, and so we cannot depict them; and yet, we can depict Christ, whose humanity is revealed to us, but whose divinity is only "glimpsed". How much "glimpsed divinity" is enough to justify a painting?
Enough to prove its existence without destroying those who beheld it.
In the Gospels, the Father's voice was heard on at least three occasions and no one was destroyed. The Spirit manifested himself at the Jordan and in the Upper Room and no one was destroyed. So what is the difference?
Did you not read the Transfiguration hymns I posted?
I did, thrice. I'm asking you because I didn't find the answer to my question therein.
You're looking for an answer to why "No-one was destroyed"? 
Putting out of your mind for the time being the selection of hymns you posted, try to follow the above exchange, paying close attention to the bold red and to the bold black.
To my question about how much glimpsed divinity is enough to justify painting an icon of a person of the Trinity, you responded with "Enough to
prove its existence without destroying those who beheld it". What is the difference here between the Son on one hand and the Father and the Spirit on the other?
For example, if you hear the Father's voice and live to tell about it, you have not been destroyed. So is that voice somehow "not enough proof" for the existence of the Father? But if it is sufficient proof for the Father's existence AND if the witnesses have not been destroyed, this would seem to satisfy your requirement of glimpsing enough divinity "to prove its existence without destroying those who beheld it", and we could justify painting an icon of that subject. Yet, your claim is that we cannot paint icons of the Father and the Spirit. There is a disconnect here somewhere.