Looking at the source, you should be able to access the tempfile name using $template->{tempfile}

#!/usr/bin/perl
use strict;
use Excel::Template::TT;
 
# some TT options
my $config = {
    INTERPOLATE => 1,
    EVAL_PERL   => 1,
};
 
# set variables for replacement
my $vars = 
  { host => {
      cmts => { name => 'name' },
      interfaces => [ {
        bundle    => 'bundle1',
        subBundle => 'subBundle1', 
        secondaries => [ {
          ipAddress  => '198.168.0.1',
          subnetMask => '255.255.255.0',
        },],},],},
};

# create object
my $template = Excel::Template::TT->new(
    filename => 'sample.xml',
    config   => $config,
    VARS     => $vars,
);

# xml template file created
my $xml = $template->{tempfile}; 
open IN,'<',$xml or die "$!";
print $_ for <IN>;
close IN;

$template->write_file('sample.xls');
system('excel sample.xls')
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