The Kunena team has announce the arrival of Kunena 6.3.0 [K 6.3.0] in stable which is now available for download as a native Joomla extension for J! 4.4.x/5.0.x/5.1.x. This version addresses most of the issues that were discovered in K 6.2 and issues discovered during the last development stages of K 6.3
Question
Editor not showing up using Kunena Crypsis B3 template
Have you activated a plugin for CSS compressing? If yes, please disable it. Maybe you have also an option to compress CSS files in your Joomla template. Then disable this option and then check the editor.