This answer was posted in response to revision 1 of the question, which was later changed.
I think you're confusing two concepts here.
Community wiki is the process of opening a post (question or answer) for community editing. Because they're designed to be collaborative, they stop earning reputation from the time they are given this status. However, those posts are still owned by whoever posted the first revision; the posts are linked on that user's profile, and that user will earn badges for votes, views, favoriting, and so on. Those posts are community wiki but not community-owned.
The other way that one might think posts would become community-owned is if an account is deleted (or a post is disassociated). But those posts aren't transferred to the Community user; they simply become ownerless. You can spot these because the user names (which may be something like "user1234" or "anon") are not links to user profiles. Other "things" associated with users, like flags and votes, can sometimes be transferred to the Community user, but posts are not.
I don't know of a way to search for community-wiki posts from the on-site search and sort by original author (owner), but you might be able to do it through SEDE. According to the schema, the Posts table has a column for CommunityOwnedDate, which might be the date the post became community wiki (if it is). There's a separate column for OwnerUserId, so you could write SQL to do what you want if you're ok with operating on data that's not completely current.