Never done this before...so this is uncharted territory for me. The Formatted Text Widget is part of core, so i accidentally removed in the Admin UI, I'd imagine it would re-add itself on restart. If not, you can always try adding it back manually ... "com.jivesoftware.community.widget.impl.FormattedTextWidget" in the same Admin Console screen.
I would definitely try recreating this on a UAT/Sandbox environment though just to be safe.
hope this helps. =)
"com.jivesoftware.community.widget.impl.FormattedTextWidget" - Did the trick, thanks!