を契機に is very formal. also see ついでに - much more common in real speech
You are entirely correct. BTW, 中国に 行ったの を景気に should be corrected to read: 中国に 行ったの を契機に. Japanese is cursed with too many homonyms and heavily reliant on kanji, as you know. However, Japanese also benefits from it. What other language would have such simple and effective device to identify intercalary months as 西向く武士（にしむくさむらい）?