Yes, as far as I could tell that's what it means. Your 'amazement equation' looks right...!

I'd phrase it as
'Both editor and poet were not so much amazed to find 'Nasha Marka' in the cigarette case, as they were with the cigarette case itself.' You can drop 'the' before their titles, if you like. It's not often done in English, and I may not be able to explain why it's ok here. If you like I can ask a friend who's a very good English teacher...
Or
'Both the editor and the poet were less amazed to find 'Nasha Marka' in the cigarette case, than they were with the cigarette case itself.' Which sounds okay, but the first construction reads more naturally to me.