I have the phone app for Italian. I just did this exercise and I wrote the translation above. It gave it to me as correct but indicated there was a typo. Saying it should have been He is not an common architect. That is of course incorrect english, so I came here to see what you have given for a translation, as the report for the phone app, is extremely limited. Just thought you would like to know.
Nice idea. However, in both wordreference and Collins, your sense of 'comune' is only given as a noun. 'Public' (adj) only gives 'pubblico', while 'municipal' (adj) gives 'municipale' and 'communale'. So probably not. And it doesn't fit with DL's other accepted options here.
The hint says, I had a typo: "He is not an common architect. " As I wrote "a common architect".
The article is an architect, that's right. But it rather depends on the word following the article, so "a common architect", "a lousy architect" is correct. As "an expensive" architect is also correct.
I see the same error, saying that "an" is correct, when it clearly isn't. But I have another point to make on this translation. What is the intended meaning of the statement "he is not a common architect"? Do they actually mean to say "he is not a conventional architect"? That is, he is a bit different, and perhaps a bit special?
You have a typo. He is not an common architect. Obviously this IS correct, because the well-known architect An (shortened from the more usual "Ann" or "Anne" for artistic effect) Common is sometimes mistaken for a man. She really needs to wear more feminine clothes and forget the Doc Martens.