What is the author's style in The Baron in the Trees by Italo Calvino?

Italo Calvino originally wrote the story in Italian and Archibald Colquhoun translated it in 1959 into English. The syntax is informal and conversational, and mixed with moments of French, Spanish and Russian as Cosimo encounters people from those places. Those languages are left without translation but are easy to loosely understand based on their context, as each instance of them is very short.