Ваш код кажется слишком сложным, но, возможно, я неправильно понимаю, что он должен делать.
Попробуйте это:
Public Function FindCodes(keywords As Range, text As String)
Dim c As Range, keywordArr, s, rv
'only look at used cells
Set keywords = Application.Intersect(keywords, keywords.Worksheet.UsedRange)
For Each c In keywords.Cells
If c.Row > 1 And Len(c.Value) > 0 Then 'Ignore first row and empty cells
keywordArr = Split(c.Value, ",")
For Each s In keywordArr
If LCase(Trim(s)) = LCase(Trim(text)) Then
'grab value from ColA and go to next cell
rv = rv & IIf(Len(rv) = 0, "", ",") & c.EntireRow.Cells(1).Value
Exit For
End If
Next s
End If
Next c
FindCodes = rv
End Function