Autocomplete field with join

Hello,
I am aiming to replace Select and Select2 fields by the autocomplete field.
I amended the field type in the Javascript side from:

        fields: [
            {
                "label": "Type d'article:",
                "name": "fac_articles_natures.articletype",
                type: 'select',
                placeholder: '',
                placeholderDisabled: false,
                placeholderValue: null
            }
        ]

To:

        fields: [
            {
                label: 'Type d\'article:',
                name: 'fac_articles_natures.articletype',
                type: 'autocomplete'
            }
        ]

it works in the sense that:
- the "labels" are listed in the fields
- when editing, the displayed "label" is correct
- when editing, I can pick another "label" and when saving, the correct "value" is stored in the database

BUT: when editing, when I click on the "label" I want, the "label" is automatically replaced by the "value" which is different due to the use of a leftjoin

    ->fields(
        Field::inst( 'fac_articles_natures.articletype' )
            ->validator( Validate::notEmpty( ValidateOptions::inst()
                ->message( 'Requis' )))
            ->options( Options::inst()
                ->table( 'fac_articles_types' )
                ->value( 'articletype_id' )
                ->label( 'articletype' ) ),
        Field::inst( 'fac_articles_types.articletype' )
    )
    ->leftJoin( 'fac_articles_types', 'fac_articles_types.articletype_id', '=', 'fac_articles_natures.articletype' )

Does anyone know how I can trick the code to avoid that?