Should I change this old meta answer since it has some risky info (RE: CW posts)?
Everything but the bit about the badge is either wrong or shady. Namely, you will get the reputation back if you perform a recalculation. Secondly, you shouldn't use Community Wiki to shield yourself from downvotes if your answer is wrong.
You should either edit the answer or (if you want the rep) add your own answer that correct's the first's bad information. (If it were me, I'd provide a new answer.)
I think that answer should be handled as any other answer given on an SE site.
You should not edit it, if you are going to change its meaning. If you think the answer is promoting something that should not be done, then you can down-vote it.
As the answer doesn't seem updated (or the user wrote something wrong), you could also add an answer for what happens now. The OP intact reports that a recalc doesn't give you back the reputation you lost because down-votes you got for a post that is then deleted; as far as I know, the the recalc triggered at sitename.com/reputation gives you back the reputation you lost because down-votes on a deleted post (and removes the reputation gain because up-votes on a deleted post).