I thought your problem was an either or. If it was true in C6 then apply one filter otherwise apply another. You are talking about adding an AND condition and this will include both conditions. The following will cater for both conditions. Paste over the top of prior workbook code.
Sheet2.AutoFilterMode = False
If Sheet12.Range("C6").Value = "TRUE" And Sheet12.Range("C7").Value = "FALSE" Then
Sheet2.Range("A1:AI1").AutoFilter 1, "Y"
Sheet2.Range("A1:AI1").AutoFilter 11, "="