84c84
< +      ->set('filename_transliteration', $transliterationActive)
---
> +      ->set('filename_transliteration', (bool) $transliterationActive)
166c166
< +      ->set('filename_transliteration', $form_state->getValue('filename_transliteration'));
---
> +      ->set('filename_transliteration', (bool) $form_state->getValue('filename_transliteration'));