Test that the CKEditor in a tool and the plugins buttons are working especially our plugins like wordcount, autosave and audiorecorder.
CK Editor v4.8.0 was released on 13-12-2017, would be good to have the latest 4.x version in Sakai 13.
Possibly a good inclusion for 12.1
Update CKEditor to 4.9.1 and update all plugins
Upgrade to CKEditor 4.7.3