Try:
Code:
Sub AutoTransliterate()
Application.ScreenUpdating = False
Dim Rng As Range, oSuggestions As Variant
Const StrDict As String = "CustomDictionary"
For Each Rng In ActiveDocument.Range.SpellingErrors
With Rng
If .GetSpellingSuggestions(StrDict).Count > 0 Then
Set oSuggestions = .GetSpellingSuggestions(StrDict)
.Text = oSuggestions(1)
End If
End With
Next
Application.ScreenUpdating = True
End Sub
Replace 'CustomDictionary' with the file name of the custom dictionary.