Let's talk in English today, because one doesn't have to be as considerate when using English as opposed to Japanese and so it's easier to complain in English.
ご質問ありがとうございます。
"Let's talk in English today,"＝「今日は英語で話そう、」
"because one doesn't have to be as considerate when using English as opposed to Japanese"＝「日本語を使うよりも英語を使うっときの方が、気を使わなくてすむから、」
"and so it's easier to complain in English."＝「だから、英語で愚痴を言う方が簡単。」
ご参考までに。
アメリカ合衆国 
