Only a value in the table column

I use a “Nationality” selection field in my form. This is displayed correctly in the form, but only the value in the table. Here is a code snippet

 }, {
        label: "Nationalität:",
        name: "mitgliederstamm.NATION",
        type: "select"     
    }, {
 
 
    { data: "mitgliederstamm.NATION",  
        "render": function (data, type, row) {
            if (type === 'display') {                
             
            }
            return data;
        },
    }, 
 
 
 
 
Field::inst( 'mitgliederstamm.NATION' )
    ->options( Options::inst()
        ->table( 'nationalitaeten' )
        ->value( 'ID' )
        ->label('Nationalität')            
        ->label( array('NATIONALITAET', 'SPRACHE') )
        ->render( function ( $row ) {
            return $row['NATIONALITAET'].' '.$row['SPRACHE'].'' ;
            } )        
    ),

Link to test case:
Debugger code (debug.datatables.net):
Error messages shown:
Description of problem: