VBA - Convert all INDIRECT into standard reference

[AmFa]

Hi,

I'd like to convert an indirect formula to the direct link. I have found various VBA codes which work fine for "simple" indirect formulas, like here from Andre: Convert indirect function to direct link

I'm wondering if it's possible to adapt the following code so that it would work for formulas that have indirect references within indirect references. like here:
=INDIRECT("'["&$B21&"]"&$C21&"'!"&XLOOKUP(MATCH($D21,INDIRECT("'["&$B21&"]"&$C21&"'!10:10"),0),$AD:$AD,$AE:$AE)&MATCH(INDIRECT(O$18&"19"),INDIRECT("'["&$B21&"]"&$C21&"'!R:R"),0))

Sub convert_indirect()
    Dim posOf, endOf, nestLevel As Integer
    Dim eval, cformula As String
    Dim r, c As Range
    Set r = Selection
    For Each c In r
        cformula = c.formula
        posOf = InStr(1, cformula, "INDIRECT(", vbTextCompare)
        If (posOf > 0) Then
            endOf = 1
            nestLevel = 1
            Do While nestLevel > 0
                Select Case Mid(cformula, posOf + 10 + endOf, 1)
                Case "("
                    nestLevel = nestLevel + 1
                Case ")"
                    nestLevel = nestLevel - 1
                End Select
                endOf = endOf + 1
            Loop
            eval = Evaluate("=" & Mid(c.formula, posOf + 9, endOf))
            cformula = Mid(cformula, 1, posOf - 1) & eval & Mid(cformula, posOf + endOf + 9 + 1)
            c.formula = cformula
        End If
    Next c
End Sub

When using the code above, it seems that it runs into a Type Mismatch error at line 22:
cformula = Mid(cformula, 1, posOf - 1) & eval & Mid(cformula, posOf + endOf + 9 + 1)

I realise it's a very convoluted query for a very convoluted formula, but if someone could help that would be great.
Thank you!