Ngram charts show a rise in the use of "atop" in the last decades so we're all the more grateful for your input. Thanks for bringing us up to speed.
Depends on the person. I'm a native English speaker who uses it. Is there some nuance to the Greek that precludes use of "atop"?
No, the Greek does not preclude it but as a native English speaker, I've not heard it for a long time. The dictionaries I tried refer to "literary use". There is one above.
Since you are accustomed to it as a native speaker we can add it to the accepted translations. Thank you for the input.
Oxford calls it literary, while Merriam-Webster doesn't specify that, so it may be a regional thing.
(In case you don't know, Oxford's the standard dictionary for UK English; Merriam-Webster, for US English except in select fields of study).