l10n vocabularies should be scaffolded with dbl10n set to true

After creating a document with a custom create layout with all the dublincore properties in Studio Designer and then installing it in webUi, when creating the document in webUI the subjects and coverage fields aren't working.

How to reproduce:

• Create a custom document type named Product (no need for additional properties)
  Configure the create layout for the Product document type
• Drag&Drop into the visual editor the dublincore schema (unselect the Title and Description as they should be already in the layout)
• Without selecting any element, select the properties tab in the editor toolbox
  Configure the layout with 3 columns
• Confirm that the default gap value is 16px and replace it with 10px
• Select the Title widget and configure its positioning inside the grid (spanning the three columns)
  • data-column: 1
  • data-column-span: 3
• Click the Description widget and make it span two columns (same procedure than used for title)
• Deploy in web-ui and confirm the grid is displayed as expected when creating a new Product document
• go to webUI and create a Product document filling all the field in the create layout

BUG

• subject and coverage fields don't load any results in the dropdown

error images in attachments