I’ve noticed something.
Right now, I’m posting without preview, and I see that *something* has replaced my standard quotes with smart quotes ... and those worked. They’re curly. My Cantonese Profanity post.
It’s another data point, anyway.
That's apparently a feature of the FR server when posting in non-HTML mode. It automatically finds strings quoted with 7-bit ASCII straight quotes and "fixes" them to use curly quotes.
The result is fine and dandy for the first iteration. But, if somebody quotes the smart-quoted post, they run into the bug, and the result is garbage.