[SceptileMaster]

Yeah I was just pointing out that saying はい in that situation may seem a little arrogant from what I've heard.

Also just as a quick comment on the sentences you post.

A: 日本語がじょうずです。
B:　いいえ、じょうずではありません。

Would be more accurate as the wa sound in ではありません is written as は not わ. Just thought I'd say in case you were unsure. But I didn't even understand the last sentence you posted so you're probably better than me at this.

Also a quick question since you seem more knowledgeable on this than me. In your first sentence why is it 日本語がじょうずです and not 日本語はじょうずです? I know that が is correct in these kind of adjective sentences (at least I think that it's that way using the common sentence (something)が好きです。as an example) but I don't know why. Well since I'm an sort of unsure about a lot of Japanese as a whole (being a beginner and since you said you were unsure) we can't even completely confirm that the sentence is valid. But I would be interested in finding out about this (although I should probably stop while before it's too late, I could be digging myself into an even deeper hole here).