Trying to find and replace some dashes, I found, that hyphens where also replaced. Obviously Atlantis (4.0.3.0.) doesn't differ between hyphens and dashes when finding/replacing.
To search for “hyphen-minus”, type “Alt+45” in the Find What box. Atlantis will only find “hyphen-minus” characters.
To search for “EN dash”, type “Alt+0150” in the Find What box. Atlantis will only find “En dash” characters.
Don’t forget to specify “Exact Match” in the “Search options”.