lol, would seam lightning just struck. There appears to be a problem in Joomla 3.9.9 affecting template styles of multilingual web sites.
www.joomla.org/announcements/release-news/5774-joomla-3-9-10.html
Note this has no impact on CB it self though. CB works fine on Joomla 3.9.9 and 3.9.10. Regardless as always I recommend making a backup before you update and using your own judgement on if you should update or not.