use strict;
use warnings;
use Win32::OLE;
use feature 'say';

my $Excel = Win32::OLE->new('Excel.Application');
$Excel->{Visible} = 1;
my $Book = $Excel->Workbooks->Add;
for my $nSht (2..$Book->Sheets->{Count}) {
    $Book->Sheets(2)->Delete;
}

my $Sheet = $Book->Sheets(1);
say $Sheet->UsedRange->Find('Go');
$Sheet->Cells(3,4)->{Value} = 'Go';
say $Sheet->UsedRange->Find('Go')->Address;
$Excel->{DisplayAlerts} = 0;
$Excel->Quit;
[download]

You may be over-complicating things. The only real complication in the SSCCE above is that Find returns undef if it fails. That is the difference in my two say statements - an undefined object cannot have an address. You may need to test for this, but I don't have your files and so can't know.

Regards,

John Davies