Correction about coercion and some typos

Hi, it's nice translation work.  I've included some possible fixes in this PR. "coercion" is difficult to translate, but I've referred the following.

http://ejje.weblio.jp/content/%E5%BC%B7%E5%88%B6%E5%9E%8B%E5%A4%89%E6%8F%9B