The question is: Is there some way to make Koivi the default editor across the whole site?
There is a hack for a wide system Wysiwyg: take a look in here -https://xoops.org/modules/newbb/viewtopic.php?topic_id=31122&forum=15&post_id=149239#forumpost149239
just note that there are some fields here and there with no HTML tags alowd and you'll see the HTML as code.
there's probably a simple way to fix it, I still did't found it (when you edit it again you see HTML well, so it means code enter the database, but not presented as should.... hope answere is on it's way)