Several small issues found

Same Problem in classes/UF_Field_Separator.php on lines 24 and 28. Another issue here: It seems that the labels on the left side are generated from the id. You missed the third parameter and mixed up the set_description method of UF_Field::factory. So here is the complete correct function:

static public function settings_fields( $field_type ) {
		$fields = array(
			UF_Field::factory( 'text', 'title', __( 'Title', 'uf' ) )
				->multilingual()
				->set_description( __( 'This title will separate different kinds of content.', 'uf' ) )
				->make_required(),
			UF_Field::factory( 'text', 'description', __( 'Description', 'uf' ) )
				->multilingual()
				->set_description( __( 'This text will appear under the title and may be used to give users directions what to do.', 'uf' ) )
		);

		return apply_filters( 'uf_field_settings_fields', $fields, $field_type );
	}

Hi again Rado,

unfortunately not all issues are fully fixed right now, we are only halfway there. First to the localization, as it seems the simplest problem: Again, check your uf-bg_BG.po file for the source pathes: It still shows ‘/Users/radoslavgeorgiev/Sites/fields/playground/wp-content/plugins/ultimate-fields’. This is more or less a cosmetical problem, but since it is the only language file you are offering, people like me probably copy and use them for their own translation. Speaking of this: I’ll send you the german translation right after finishing this post.

On to the UF_Field_Separator.php: You fixed the labels, but left out the descriptions. Line 24 should be
->set_description( __( 'This title will separate different kinds of content.', 'uf' ) )
analogue line 28 should be
->set_description( __( 'This text will appear under the title and may be used to give users directions what to do.', 'uf' ) )

Now to the placing of the options pages: Halfway done, too. Let us assume the following: I created three containers, each of it with a slug like container1, container2, container3. When I place container1 in the main menu, I now could place container2 and container3 as sub menu items of container1. But still the url of the first placed container1 is changed to whatever is placed next under it, i.e. yourdomain.com/wp-admin/container2.

And the most important Problem still exists: The Urls in such a case are invalid! yourdomain.com/wp-admin/container2 for example should be yourdomain.com/wp-admin/admin.php?page=container2
When I now open this link from the browser bar (ONLY when placed under another Ultimate Fields page), I get a message that I do not have the privileges to view the page.

Additionally, when I place the page under another page named with slug, a 404 error occurs. I tried change the page slug to a full link like admin.php?page=container1, but in this case, the options page appears nowhere.

I’d like to thank you for your fantastic work so far!