As of very recently, pluralization bugs have appeared in the system. I could have sworn that these used to look correctly; it seems like a very recent change has caused this bug.
When someone posts a comment, and it's loaded in someone else's browser by the heartbeat, it used to properly show "show 1 more comment", but it now shows "show 1 more comments".
Also, when someone posts a new answer, it used to show "1 new answer to this question", but now it shows "1 new answers to this question". I don't have a screenshot for this, but I could have sworn it used to display correctly earlier.
Is this a side effect of the recent change that caused server errors on Stack Overflow?