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.
does this ban block you from (continuing) to change your existing comments?
Not in the slightest.
To my knowledge yes.
deleted by creator
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.
You absolutely can edit comments on subs you are banned in. Source: I did it just last month.