You're missing a  my( $hl, $path, $tool, $usr, $data, $general ) = @_; Instead of

sub _insertData 
{
    my $path = shift;
    my $tool = shift;
    my $usr = shift;
    ...
    $hl->itemCreate($path,0,-text=> $data->{$usr}->{$tool}->{feature},
+-style => $general);
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You're creating a sub that takes arguments, so pass it all the variables its using