[Sashimister]

Originally Posted by KyleGoetz

He uses 私は in the second sentence. But I'm not entirely sure that qualifies as a "big mistake" because 私は is correct grammar if not native-sounding.

That first-person pronoun there is good. It's a rare case where you sound better using one than without.

What about mixing です with って in the second sentence?

No problem. There's no way you can get rid of that って from 流行ってる or 流行っている, that is unless you use 流行（はやり）の.

Also, I never got a chance to learn if Japanese use parentheses and dashes as often as in English, so I'm not sure if that's a clue. I use () exactly the same in both languages, but I'm admittedly no more than an upper-intermediate or lower-advanced speaker.

There aren't really rules reagrding parentheses. It's ok as long as yo use them in moderation. Dashes, however, are rarely used.

I guess I'm telling the answer now as I don't want to derail from the thread any further.

Kim's use of 活躍しています is what told me he wasn't a native speaker. We just don't say that about ourselves as it's the same thing as praising yourself. You can say it about others, though. The only time you can say it about yourself is when you are clearly joking.