I have used two ways to find your strings.
First, if I place your string in Cell(1,1) (I also added the #c44# to that string)
in Cell(1,2) I entered formula:
=FIND("#c44#",A1,1)
Note that the CASE must match or it will not find the string!
The second method is the following Function
Option Explicit
Function Find_Pound()
Dim strString As String
Dim strFind1 As String
Dim i As Integer
'"#CK# Site B: Umbau der IDU vom in Delta-Cabinets und Auflage der #c44# STM-1 auf ODF"
strString = Sheet1.Cells(1, 1)
strFind1 = "#CK#"
i = InStr(1, strString, strFind1)
If i > 0 Then
MsgBox "Found: '" & strFind1 & "' at position: " & i
End If
strFind1 = "#c44#"
i = InStr(1, strString, strFind1)
If i > 0 Then
MsgBox "Found: '" & strFind1 & "' at position: " & i
End If
End Function