The Kunena team has announce the arrival of Kunena 5.1.18 [K 5.1.18] which is now available for download as a native Joomla extension for J! 3.9.x. This version addresses most of the issues that were discovered in K 5.1 and issues discovered during the development stages of K 5.1.
New Post Topic Icons - not showing "New" version
I'm not sure If I understand right. You mean the icons at recent topics or at the index page? At Recent Topics has never been a second icon for New. Only the color changes if you use bootstrap or font awesome icons.