I downloaded my entire reddit activity and have been going through it slowly, changing all my comments to links back to themselves. Today I got this:
Hello, You have been permanently banned from participating in r/funny because you broke this community’s rules. You won’t be able to post or comment, but you can still view and subscribe to it.
If you have a question regarding your ban, you can contact the moderator team by replying to this message.
Reminder from the Reddit staff: If you use another account to circumvent this subreddit ban, that will be considered a violation of the Content Policy and can result in your account being suspended from the site as a whole.
To my knowledge, you can edit comments after being banned. When I was on Reddit, before I deleted my account, I had been banned from one subreddit I participated in pretty regularly when a new mod joined and needed to be quickly removed for abuse. I was banned mid-discussion, but I was still able to go back and edit my comments in that subreddit.