Prepositions are always tough to render in another language since 1. they have so many meanings and 2. they're are regional differences. That said, I think 'at' expresses the same idea as 'in' here. Report it and hope it'll be accepted in the future....(or is it 'at' the future, hmm?).
I second this opinion. I read news in Italian regularly and I often see "in piazza". It means the same as "in the streets" in English (regarding the civil protests, for example). In English you don't say "protests in the square", you say "protests in the streets"! And Italian you probably don't say "migliaia in strade" but "migliaia in piazza", meaning the same. Acttualy "in the streets" is the correct translation and "in the square" is not correct since it loses the meaning. Please correct me if I'm wrong.
al_ex_s: "Protests in Tiananmen Square" -- Headline across the globe in 1989! "Charging Riot Policemen Beat Protesters in Prague Square" , headline in 1968. "Protesters detained after rally near Moscow's Red Square, 2014. Etc. Media reports routinely talk about 'protests in the square' if in fact the location of the protests is a "square".
"Piazza" is not a plaza (Is that supposed to be a square in the Spanish style?) in the Italian style. It's just a square. Tian'anmen Square, the Place de la Concorde, Plaça de Catalunya in Barcelona... these are all "squares" in English, "plazas" in Spanish, and "piazze" in Italian.
Strange how sometimes you have to translate "piazza" as "public square" (marked wrong as just "square"), and other times you write "square" (and get it marked wrong, saying it should be "public square!") I understand why either could be correct, but if you are talking about a piazza (a place), you would never be referring to the geometric shape (a square). I wish they would be consistent in always counting "public square" as correct, instead of flipping back and forth.