Inicialmente para que funcione en form.php, en línea 93 añadir: if ($value !== null && $filter) { if(is_array($value) === FALSE){ $value = htmlspecialchars($value, ENT_COMPAT, APP_CHARSET); } } //Se debe mejorar

form2.php

<?php

/**
 * KumbiaPHP web & app Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://wiki.kumbiaphp.com/Licencia
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@kumbiaphp.com so we can send you a copy immediately.
 *
 * @category   KumbiaPHP
 * @package    Helpers 
 * @copyright  Copyright (c) 2005-2012 KumbiaPHP Team (http://www.kumbiaphp.com)
 * @license    http://wiki.kumbiaphp.com/Licencia     New BSD License
 */

/**
 * Helper para Formularios
 *
 * @category   KumbiaPHP
 * @package    Helpers
 */
class Form2 extends Form {

    /**
     * Crea campos check que toma los valores de un array de objetos
     *
     * @param string $field Nombre de campo
     * @param string $show Campo que se mostrara (opcional)
     * @param array $data Array('modelo','metodo','param') (opcional)     
     * @param string|array $attrs Atributos de campo (opcional)
     * @param string|array $value (opcional) Array en select multiple
     * @return string
     */
    public static function dbCheck($field, $show = NULL, $data = NULL, $attrs = NULL, $value = NULL) {
        if (is_array($attrs)) {
            $attrs = Tag::getAttrs($attrs);
        }

        // Obtiene name, id y value (solo para autoload) para el campo y los carga en el scope
        extract(self::getFieldData($field, $value), EXTR_OVERWRITE);

        $checks = '';

        //por defecto el modelo de modelo(_id)
        if ($data === NULL) {
            $model_asoc = explode('.', $field, 2);
            $model_asoc = substr(end($model_asoc), 0); //No se elimina el _id, porque no debe venir
            $model_asoc = Load::model($model_asoc);
            $pk = $model_asoc->primary_key[0];

            if (!$show) {
                //por defecto el primer campo no pk
                $show = $model_asoc->non_primary[0];
            }

            $data = $model_asoc->find("columns: $pk,$show", "order: $show asc"); //mejor usar array
        } else {
            $model_asoc = Load::model($data[0]);
            $pk = $model_asoc->primary_key[0];

            // Verifica si existe el parámetro
            if (isset($data[2])) {
                $data = $model_asoc->$data[1]($data[2]);
            } else {
                $data = $model_asoc->$data[1]();
            }
        }

        $i = 1;
        $j = 4;
        foreach ($data as $p) {
                $checks .= "<label class=\"checkbox\">";
                $checks .= Form::check($id . '[]', $p->$pk);
                $checks .= htmlspecialchars($p->$show, ENT_COMPAT, APP_CHARSET) . '</label>' . PHP_EOL;
                /*if($i==1){
                    $checks .= '<div class="row-fluid">'. PHP_EOL;
                }
                
                $checks .= '<div class="span3">'. PHP_EOL;
                $idx = $id . '_' . $p->$pk;                
                $namex = $id . '[]';
                $checks .= "<label class=\"checkbox\"><input id=\"$idx\" name=\"$namex\" type=\"checkbox\" value=\"{$p->$pk}\"";
                // Si es array $value para select multiple se seleccionan todos
                //var_dump($value); die();
                $checked = '';
                if (is_array($value)) {
                    if (in_array($p->$pk, $value)) {
                        $checks .= ' checked="checked"';
                    }
                } else {
                    if ($p->$pk == $value) {
                        $checks .= ' checked="checked"';
                    }
                }
                $checks .= " $attrs>" . htmlspecialchars($p->$show, ENT_COMPAT, APP_CHARSET) . '</label>' . PHP_EOL;                                
                $checks .= '</div>'. PHP_EOL;
                
                if($i===$j){
                    $checks .= '</div>'. PHP_EOL;
                    $i=0;
                }
                $i++;*/
        }
        
        /*if($i !== 1){
            $checks .= '</div>'. PHP_EOL;
        }*/

        return $checks . PHP_EOL;
    }

}