

Not familiar with moderation capabilities on PieFed, but something that can aid when moderating is having RSS tracking your communities. Even if the post gets deleted, if the RSS reader fetched the post in the time frame before that, it gets stored in your reader’s (preferably persistent) cache.

















Additionally, someone in an external instance can pull older posts by searching their links in the search page, often even if you get the link from yet another instance. Same for comments.
Only caveat is if the original post is unreachable, e.g. if communications were blocked (“instance defederated”), DNS or firewall is misbehaving at instance level, the instance is dead, etc.
Also, boosting, a microblogging thing, allows spreading posts and comments further, though a bit more indirectly.