[Theme Horse Support Team]

Hi info39,
If you change the code then while updating to our new version all your customisation code will be lost. So we recommended not to change the code.
Just create two file
1> style.css and
2>functions.php

Under functions.php adding this code its correct
<?php load_theme_textdomain( 'interface', get_stylesheet_directory() . '/languages' ); ?>

and under style.css add the below code.

/*
 Theme Name:   Interface Child
 Theme URI:    https://www.themehorse.com
 Description:  Interface Child customization
 Author:       Theme Horse
 Author URI:   
 Template:     interface
 Version:      1.0.0
 Tags:         
 Text Domain:  interface
*/

@import url("../interface/style.css");

Thank you!