Laravel 5.6. Form validation in the custom package

Question

I'm making custom package and have problems with localized validation attribute output. How can I fix this problem? It returns post_localizations.en.post_title instead of localized string Post title (EN)

I have input in my form: <input type="text" name="post_localizations[ru][post_title]" />

And validations in my Controller is:

$this->validate($request, [
            'post_localizations.*.post_title' => 'required|max:70'
        ], trans('namespace::validation'));

validation.php in my package:

'attributes' => [
        'post_localizations.*.post_title' => 'Post title (EN)'
]

Loading translations in in boot method of the Provider:

$this->loadTranslationsFrom( __DIR__ . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . 'resources' . DIRECTORY_SEPARATOR . 'lang', 'namespace');

All are works fine if I'm inserting my attribute to default laravel resource/lang/en/validation.php. Also all are fine if string of input name simple like post_title:

<input type="text" name="post_title" />

'attributes' => [ 'post_title' => 'Post title' ]