Hi Wilco,
will this work on the Mac
Sub ertert()
Dim x, y(), i&, j&, k&, n&, sp, s$
With Sheets("What I Have")
    x = .Range("A1:B" & .Cells(Rows.Count, 1).End(xlUp).Row).Value
End With
ReDim y(1 To UBound(x) * 4, 1 To 3)
For i = 2 To UBound(x)
    If Len(Trim(x(i, 1))) Then
        sp = Split(x(i, 2), ";")
        For j = 0 To UBound(sp)
            n = n + 1: y(n, 1) = x(i, 1)
            y(n, 2) = Val(sp(j)): s = Split(sp(j), ",")(1)
            For k = 1 To 10
                If Application.Roman(k) = s Then y(n, 3) = k: Exit For
            Next k
            If k > 10 Then y(n, 3) = s
        Next j
    End If
Next i
With Sheets("What I need")
    .UsedRange.ClearContents
    .Range("A1:C1").Value = Array("Source", "Target", "Weight")
    .Range("A2:C2").Resize(n).Value = y()
    .Activate
End With
End Sub