Repeater Kirki Hooks. First attempt in a good direction, maybe

kirki-hooks.php

<?php

add_action( 'customize_register', 'kirki_hooks_customize_register' );

function kirki_hooks_customize_register( $wp_customize ) {
	class Kirki_Customize_Control_Repeater_Setting extends WP_Customize_Setting {

		/**
		 * In Repeater, one setting is one row full of settings
		 * fields save all the fields and their types
		 *
		 * @var array
		 */
		public $fields = array();

		public function __construct( $manager, $id, $args = array() ) {
			parent::__construct( $manager, $id, $args );
		}

		public function get_fields() {
			return $this->fields;
		}
	}

	class Kirki_Customize_Control_Repeater_Control extends WP_Customize_Control {
		public $type = 'jt-select';

		public function enqueue() {
			wp_enqueue_script( 'jt-customize-controls', plugin_dir_url( __FILE__ ) . 'kirki-hooks.js', array( 'jquery' ) );
		}

		public function get_fields( $setting_key = 'default' ) {
			if ( ! isset( $this->settings[ $setting_key ] ) )
				return array();

			return $this->settings[ $setting_key ]->get_fields();
		}

		public function to_json() {

			// Call parent to_json() method to get the core defaults like "label", "description", etc.
			parent::to_json();

			$settings_keys = wp_list_pluck( $this->settings, 'id' );
			$this->json['value'] = array();
			foreach ( $this->settings as $key => $setting ) {
				$this->json['rows'][ $key ] = $this->get_fields( $key );
				$this->json['value'][ $key ] = $this->value( $key );
				$this->json['link'][ $key ] = $this->get_link( $key );
			}

		    // The control choices.
		    $this->json['choices'] = $this->choices;

		}


		public function content_template() {
			?>
			<#
				if ( ! data.rows ) {
					return;
				}

				var rowFields, fields;

				for ( var i = 0; i < data.rows.length; i++ ) {
					rowFields = data.rows[ i ];

					for ( var j = 0; j < rowFields.length; j++ ) {
						field = rowFields[j];
						link = data.link[i];
						value = data.value[i];
						console.log(data);
						console.log(link);

						#>

							<label>

								<# if ( data.label ) { #>
									<span class="customize-control-title">{{ data.label }}</span>
								<# } #>

								<# if ( data.description ) { #>
									<span class="description customize-control-description">{{{ data.description }}}</span>
								<# } #>

								<input type="text" {{{ link }}} value="{{{ value }}}" />

							</label>

						<#
					}

					#>
					<hr/>
					<#
				}
			#>




			<?php
		}
	}

	// Register the control type.
	$wp_customize->register_control_type( 'Kirki_Customize_Control_Repeater_Control' );

	$wp_customize->add_section( 'themename_test', array(
		'title'          => __( 'Test', 'themename' ),
		'priority'       => 35,
	) );

	$wp_customize->add_setting( new Kirki_Customize_Control_Repeater_Setting( $wp_customize, 'setting_1', array(
		'fields' => array(
			array(
				'id' => 'subsetting_1',
				'type' => 'text',
				'default' => 'subsetting1'
			),
			array(
				'id' => 'subsetting_1',
				'type' => 'text',
				'default' => 'subsetting2'
			)
		)
	) ) );

	$wp_customize->add_setting( new Kirki_Customize_Control_Repeater_Setting( $wp_customize, 'setting_2', array(
		'fields' => array(
			array(
				'id' => 'subsetting_1',
				'type' => 'text',
				'default' => 'subsetting1'
			),
			array(
				'id' => 'subsetting_1',
				'type' => 'text',
				'default' => 'subsetting2'
			)
		)
	) ) );

	$settings = array( 'setting_1', 'setting_2' );
	$wp_customize->add_control( new Kirki_Customize_Control_Repeater_Control( $wp_customize, 'control_id', array(
		'section' => 'themename_test', // Required, core or custom.
		'label' => __( 'Setting Test' ),
		'settings' => $settings
	) ) );
}