Hi Ross,
I waste most of my time trying to play guitar and trying to use excel
so I found your post interesting.
If you haven't yet solved the problem with sharps the following worked
for me:
Sub Sharp()
If ActiveCell.Value < "" Then
Dim Chord As String
Chord = ActiveCell.Value
With ActiveCell
.Value = Left(Chord, 1) & "#" & Right(Chord, Len(Chord) - 1)
.EntireColumn.AutoFit
End With

End If
End Sub

I added the autofit line to improve the chord's visibility.
I hope this is useful.
Ken Johnson