The built-in Find function only supports a limited set of regular expressions. If you want to use the usual standard standard expressions, you need to do something like this:
Dim regExp As Object
Set regExp = CreateObject("vbscript.regexp")
With regExp
.Pattern = "(Event Handling \(EH\)|Event Handling)"
.Global = True
Selection.Text = .Replace(Selection.Text, "Replaced")
End With
, . , Event Handling \(EH\) "(Event Handling \(EH\)|Event Handling)", Event Handling , , , (EH).
, Word, Find, - Event Handling \(EH\) :
'Settings
With Selection.Find
.Replacement.text = "Replaced"
.Forward = True
.Wrap = wdFindAsk
.Format = False
.MatchCase = False
.MatchWholeWord = False
.MatchWildcards = True
.MatchSoundsLike = False
.MatchAllWordForms = False
End With
'First find
With Selection.Find
.text = "Event Handling \(EH\)"
.Execute Replace:=wdReplaceAll
End With
'Second find
With Selection.Find
.text = "Event Handling"
.Execute Replace:=wdReplaceAll
End With