The Query Id attribute must be numeric. I got the following to work:

for (10000..10001) {
    die Win32::OLE->LastError() unless (push @Triggers, $TriggerSet->C
+reate(0));
    $Triggers[$#Triggers]->{Id} = $_;
    $Triggers[$#Triggers]->{Subscription} =
        qq{<QueryList>
          <Query Id="$_" Path="Microsoft-Windows-NetworkProfile/Operat
+ional">
            <Select Path="Microsoft-Windows-NetworkProfile/Operational
+">*[System[(EventID="$_")]]</Select>
          </Query>
        </QueryList>};
    die Win32::OLE->LastError() 
  unless (my $values = $Triggers[$#Triggers]->ValueQueries->Create("ev
+entId", "Event/System/EventID"));
    $Triggers[$#Triggers]->{Enabled} = 1;
}
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The relevant, magic change is matching

    $Triggers[$#Triggers]->{Id} = $_;
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and

    <Query Id="$_" Path="Microsoft-Windows-NetworkProfile/Operational"
+>
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Maybe you can change both to be non-numeric, but with that change, I created tasks that I was able to view them afterwards.

Some stylistic notes:

Don't use double-quoted strings with (many) escaped backslashes in them. Instead, use one of the alternate quoting mechanisms, like qq{...} to prevent excessive backslashitis.

For easier testing, do both calls at the end of your program:

warn "Testing query";
$RootFolder->RegisterTaskDefinition("OLE-Test",$TaskDefinition,1,undef
+,undef,3);
warn "Query OK, installing task";
$RootFolder->RegisterTaskDefinition("OLE-Test",$TaskDefinition,6,undef
+,undef,3);
print Dumper $TaskDefinition->{XmlText};
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