I think you may have done. 
Side-stepping the UI and deleting the (supposedly) undeletable topics can have some unforeseen consequences.
Though it’s an easy fix. 
(using the rails console)
There are a couple of hidden site settings where you’ll need to replace the topic_id for a ‘new’ topic you can have in its place.
There’s a bit more detail in this post - How to regenerate FAQ and TOS pages? - #2 by gerhard
And here’s the hidden settings guide - Hidden Site Settings Reference Guide
The two you want are privacy_topic_id and tos_topic_id