The first time you rolled an edit back. Say someone asked a bad question, then someone else edited it, but missed the point of the question in the edit. (If you have enough rep, or if it was your question) you can undo the edit by rolling it back. You get a badge for this.
I like the idea of rewarding people for helping others, but:
As you point out, it's incredibly hard to quantify what qualifies, or the threshold.
There's already multiple badges for editing posts. This is essentially the same idea, as you're only supposed to edit posts to improve their quality.
You must access the site via either the full web experience, or the mobile site. But: the front page is not enough. What is enough? Who knows (see the Fanatic badge. This is to avoid gaming via scripts).
RSS etc doesn't count because there's no relationship between the RSS feed and your user account.
All Time based badges are based on UTC days.
This happens all the time to people who are not in the GMT time zone. You seem to be in CST. So if you visit Monday around noon, then Tuesday evening, a whole UTC day will have passed between Monday 6pm and Tuesdays 6pm. Same thing happened to me around 90 days.
With regard to the cloud tag badge, you do indeed have 100 points in that tag, but you haven't yet met the second requirement of 20 answers. You got those 100 points from only six answers.
From the help center:
As for Strunk & White, this one is confusing because it has some hidden restrictions. For instance, editing only tags doesn't count. I didn'...
Regular badges will not be revoked except in very special circumstances.
How do "badges" work?
Regular badges, however, once earned, are yours to keep. Even if the criteria by which you earned a badge have changed (the post was deleted, you got downvoted, etc.) you get to keep your badge. If you qualify for the same badge again (another post ...
This post only answers the question about Strunk and White
PS: If you want to know the progress of some badges (especially editor badges), go to one of review pages then hover on green bar.
According this query from data.stackexchange, until Dec 7 you just have 56 edits count to badge. Between Dec 7 until now (Dec 10) you have 25 edits. So 56 ...
Score, here, is total upvotes minus total downvotes.
As far as I know it's worked that way since (almost) the beginning.
To quote from the SE FAQ:
A tag score is basically the combined total of all the upvotes (+1) and downvotes (-1) you've accumulated on answers under that specific tag (votes on questions do not count). Acceptance of an answer doesn't ...