Tag comments as !Important
Add a button or some way to allow the commenter or Owner to mark comments as "Important". This would visually change the comment itself as well as the pin, if it's pinned. The button or status could also be clicked again/removed to allow the comment to go back to normal status and not Important.
Attached is a quick example of what could be done, to allow the eyes to quickly see what's been marked priority over other comments.