Rebel8 was outed. It did show up on her timeline.
To answer your question, Jgnat, a group name shows up on your timeline under "recent activity" or in your newsfeed when you join or are added. It does not show up on your timeline/newsfeed when you leave a group (there is no "so-and-so has left such-and-such group" notification on the newsfeed). Also, I believe there is a distinction between a "closed" group (name still shows up on newsfeed but nobody can see the contents) and a "secret" group (security is allegedly a little tighter though who knows, with Facebook settings, which change and glitch out all the time).
Also, I did not receive any email notification when I was added. Neither did Dagney. I didn't know for a couple of days, until I logged in (and then it was just buried in my notifications drop-down).
Now that the group has been made "open to all", there is even more potential for outing people who haven't yet realized they've been added. It's not as though you've removed all of the force-added people (some of whom you admit were added by your own volunteers and members) and then PM-d them to invite them properly. You've made the group open and increased the likelihood of outing, and you're just saying, "well, they can still leave or complain if they want to", even though many still may not realize they've been added.
How many people have yet left (after realizing they were added) or how many they've been replaced by is an irrelevant, moot point. I think you're at least trying to be honest and do something about it, Juan, in contrast with some other board members, but "only a FEW people have complained about being outed or potentially outed" isn't exactly any comfort to them. I mean, your argument is, "Hey, we only messed up or potentially messed up a FEW people's lives, only compromised a FEW people's privacy. That we know of. So far."