A couple of days ago, I was chatting with my Jewish friend over Skype. He and I are really good friends. At that time my British friend was staying at our house. Although he didn't join our conversations, while sitting next to me and working with his PC, he was listening to our conversations. We were speaking in English at the time.
My Jewish friend told me that he finished reviewing 2000 Kanji (Kanji is one of our characters in Japanese language). When I heard his story, I thought it was great! However, instead of saying congratulations, and it was great I said that there were more than 2000 kanji. It isn't enough for you to read something in Japanese. Your Kanji level is the same as Japanese middle school kids. You have to study more Kanji, and your next goal was 3000. I knew that he already has memorized 2000 Kanji. He reviewed all of them. So, I would like to encouraged him.
When my British friend listened to that, he told me, "Yumi!!! It's really rude to David! I know it's a Japanese way, and not a Western way. However, you should say, "Congratulations!" first to him." Until I heard it from Martyn (My British friend's name is Martyn), I never ever thought my comment sounded rude to David. I was shocked. Of course, David is my good friend, and he knows Japanese culture very well. So, he didn't say that I offended him at all. Although I just wanted to encouraged him, my encouraging comment sounded negative to both my British friend and Jewish friend.
Thinking about this, I think Japanese language is negative. I think all languages relate to their own culture tightly. So, if you have been learning other languages, I really want you to learn the culture at the same time.