A setting to allow non-post-owner(s) to check checkboxes (without making the post a wiki)

Checking those boxes is editing your post by definition. So you are actually asking limiting editing rights and one setting more: who and when can mark checks, and where.

And as usually when I can’t offer useful answer, quite often actually…, I’m asking a meta thing: which one is actual issue now: tuned ability to edit a wiki, or you can’t trust your team members are following your orders and guidelines?