Most often you’re not the only person noticing a problem. If all the feedback they get from the various different users isn’t enough, they’ll ask for details. But they might not ask you, but one of the 999 other people with that error. So, getting an actual reply from them is like winning the lottery.
However, there’s always a status displayed which might change to “Fix implemented in future iOS version” (or something alike). You can read this as “thanks, archiving”.
Fun fact: If you notice a bug being fixed in an update, you can close the feedback items yourself. And you can even add something nice like “thanks for fixing” before closing it.