Condition based replacements of Cells with other values

Not sure why you need to replace - could not just reverse the logic of your summary calcs ?

If you need to replace then it would be best to first run an Edit -> Replace for each value (1 to 5 [ignoring 3]) replacing the digit with a separate character: eg 1 to @ and 2 to ^ etc...

Once complete run a subsequent Edit -> Replace for each value converting @ to 5, ^ to 4 etc...

(avoid using *, ~, ? characters)

You can replicate the process in Code, in basic terms:

Sub Example()
    Dim vFW As Variant, vRW As Variant
    Dim lngR As Long
    On Error GoTo ExitPoint
    Application.ScreenUpdating = False
    vFW = Array(1, 2, 4, 5)
    vRW = Array("^", "@", "[", "]")
    For lngR = LBound(vFW) To UBound(vFW) Step 1
        With Selection
            .Replace vFW(lngR), vRW(lngR)
        End With
    Next lngR
    For lngR = LBound(vFW) To UBound(vFW) Step 1
        With Selection
            .Replace vRW(lngR), vFW(UBound(vFW) - lngR)
        End With
    Next lngR
ExitPoint:
    Application.ScreenUpdating = True  
End Sub

above is geared to run against the active selection at run-time

A quicker alternative might be:

Sub Example()
    Dim rngArea As Range
    For Each rngArea In Selection.Areas
        With rngArea
            .Value = .Parent.Evaluate("IF(ISNUMBER(" & .Address & "),1+5-" & .Address & ",REPT(" & .Address & ",1))")
        End With
    Next rngArea
End Sub