You could also try fixing on a later step. Put the following small Perl script into chop-sql-comma.pl:

my $sql = do {local $/; <>};
$sql =~ s/\( ([^()]+) \) , \n\)/($1)\n)/x;
print $sql;
[download]

Then run from a command prompt with perl "edit in place" mode:

C:\Users\...>perl -i.bak chop-sql-comma.pl CUSTOMER_NEW.txt
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Update - after some more digging golfed to (again windows cmd prompt):

perl -Mv5.14.0 -i.bak -e^
 "local $/;print <> =~ s/\( ([^()]+) \) , \n\)/($1)\n)/xr"^
  CUSTOMER_NEW.txt
[download]