Hello Robkk,
I tried the moderation plugin you suggested but it has not been updated in over 3 years so it does not work for me.
I read here https://codex.bbpress.org/moderation-and-blacklisting/ that discussion settings should be applied for bbpress but that also does not work.
For whatever reason anyone can immediately post replies without having to wait for moderation.
Under Settings > Discussion > Before a comment appears – I have the checkbox selected for “Comment must be manually approved” however that does not happen.
Thanks,
Dustin