On my Mac, editing a comment node’s comment text does not wrap the text if the entered string is longer than the comment node box. Instead, the text is cut-off at the edge of the node. Editing of the text itself is still successful, but the text box does not wrap and does not scroll over to the cursor.
This happens on Windows too. What I do is I use Shift+Enter to manually add a new line string while editing. I hope Epic address this issue soon.
I was able to reproduce this and have entered a bug report, UE-30410, to be assessed by the development staff.