Prestashop 1.7 - Bug FormBuilder on Cms Page Category - module

Question

I wrote a Prestashop module to add two fields in the CMS Category but the render is wrong.
My source code:
<?php
class NewsSlider extends Module {
public function hookActionCmsPageCategoryFormBuilderModifier(array $params) {
$formBuilder = $params['form_builder'];
$locales = $this->get('prestashop.adapter.legacy.context')->getLanguages();
$formBuilder->add($this->name.'_cover_lang',
\PrestaShopBundle\Form\Admin\Type\TranslatableType::class,
[
'type' => \Symfony\Component\Form\Extension\Core\Type\FileType::class,
'label' => $this->l('Image de couverture'),
'options' => [
'required' => false,
'constraints' => [
'mimeTypes' => [
'image/png',
'image/jpeg'
],
'mimeTypesMessage' => 'JPEG/PNG',
]
],
'required' => false,
]
);
$formBuilder->add($this->name.'_header_lang',
\PrestaShopBundle\Form\Admin\Type\TranslateType::class,
[
'type' => \PrestaShopBundle\Form\Admin\Type\FormattedTextareaType::class,
'label' => $this->l('Entête de la page'),
'locales' => $locales,
'hideTabs' => false,
'required' => false
]
);
$languages = Language::getLanguages(true);
foreach($languages as $lang){
$content = $this->getCMSHeader($params['id'], $lang['id_lang'], $isCategory);
if(is_string($content) && strlen($content)) {
$params['data'][$this->name.'_header_lang'][$lang['id_lang']] = $content;
}
}
$formBuilder->setData($params['data']);
}
}
?>
You can see the render here.
And I wrote exactly the same code for the CMS Page (hookActionCmsPageFormBuilderModifier) and it's working. Why is it different?