I created the isosurface with the short script below.

#!perl
use strict;
use Getopt::Long;
use MaterialsScript qw(:all);

my \\\$doc = \\\$Documents{"Cell.xsd"};
my \\\$result = Modules->DFTB->Energy->Run(\\\$doc, Settings(Quality => "Coarse",
SKFLibrary => "CHNO",
CalculateChargeDensity => "FieldAndIsosurface",
Smearing => "0.01",
));

# set field and parameter
my \\\$field = \\\$doc->AsymmetricUnit->Fields("DFTB+ total electron density");
my \\\$isosurface = \\\$field->Isosurface;
\\\$field->ColorMap->ColorMapMaxValue = \\\$field->FieldMax;
\\\$field->ColorMap->ColorMapMaxValue = \\\$field->FieldMin;
\\\$field->ColorMap->ColorMapColorSpectra = "Rainbow";
\\\$field->ColorMap->ColorMapNumberOfBands = 128;
\\\$field->ColorMap->ColorMapShowLegend = "Yes";
printf "%s IsHidden: %s\\n", \\\$field->Name, \\\$field->IsHidden;

As a result, "printf "%s IsHidden: %s\\n", \\\$field->Name, \\\$field->IsHidden;" is "DFTB+ total electron density IsHidden: 1".
How to "DFTB+ total electron density IsHidden: 0"??
If anyone knows about it, I would appreciate it if you could teach me.
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***append***
The pl file and xsd file used are as follows.

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