Sub ShiftTimePlus4()
Dim rng As Range
Dim txt As String
Dim re As Object, matches As Object, m As Object
Dim h As Integer, mi As Integer
Dim newTime As String
Set re = CreateObject("VBScript.RegExp")
re.Global = True
re.Pattern = "\b([01]?\d|2[0-3]):([0-5]\d)\b"
Set rng = ActiveDocument.Content
txt = rng.Text
Set matches = re.Execute(txt)
' Обрабатываем с конца, чтобы не сбить позиции
Dim i As Long
For i = matches.Count - 1 To 0 Step -1
Set m = matches(i)
h = CInt(m.SubMatches(0))
mi = CInt(m.SubMatches(1))
h = (h + 4) Mod 24
newTime = Format(h, "00") & ":" & Format(mi, "00")
rng.Start = m.FirstIndex
rng.End = m.FirstIndex + m.Length
rng.Text = newTime
Next i
MsgBox "Готово! Время сдвинуто на +4 часа."
End Sub