redaktoro

The -oro is a fossil, not a suffix. Esperanto forms agent nouns with -ist- (a professional) or -ul- (a person characterised by something), and it has no -or- suffix at all. So redaktoro is not redakt- plus an agent ending in any Esperanto sense: it is one borrowed Latin agent noun, imported already assembled, exactly like motoro, doktoro, traktoro, profesoro and direktoro. The -or- on all of them is Latin morphology showing through the skin of an Esperanto root.

Which raises a fair question: could you say redaktisto instead? You can, and it is understood, and some writers prefer it precisely because it is transparent. But redaktoro is what the movement's own periodicals have printed for a century, and a title on a masthead is not the place to be inventive. Learn redaktoro; recognise redaktisto.

The family around it. Redakti is the verb, to edit; redaktado the work of editing; redakcio the editorial office or the editorial team, a separate borrowed noun that catches people out because it does not look derived from redakti either. Alongside them sit verki (to write a work), aŭtoro (the author), eldoni (to publish) and eldonejo (the publishing house).

What the job is. A redaktoro decides what runs and fixes what runs badly. If you only need "someone who corrected my text", the verb korekti says that without promoting anyone.