I gave up on filing feedback after way too many reports vanished into a black hole and were never even acknowledged, much less actually fixed.
Any issue I might report would also have to be reported by hundreds to thousands of other users for Apple to even notice it in the constant flood of other feedback reports and automated analytics reports — basically, unless an issue is found by a sufficiently annoyed Apple engineer, a sufficiently annoyed Apple executive, or is widespread enough to get picked up by non-tech media, it's unlikely to rise to a high enough priority level to get into the active bugfix queue except by sheer accident.