I can edit autocompleter output as an example if user write con so autocompleter lists for example closing but I want to autocompleter lists only words which have letter c,o,n immediately adjacent side by side. For example content.
You can add an insertMatch method on your completer. You can put your display text in the value property on the match.
insertMatch: function(editor, data) {
editor.completer.insertMatch({value: data.caption});
}