Handling Multi-level custom taxonomy hierarchy

You’ll probably have to run a cycle using get_terms() paired with the ‘parent’ attribute.

$args = array( 'parent' => 0 );
$parents = get_terms( array( 'custom-tax' ), $args );
foreach ( $parents as $parent ) {
    echo $parent->name;
    $args['parent'] = $parent->term_id;
    if ( $children = get_terms( array( 'custom-tax' ), $args ) ) {
        foreach ( $children as $child ) {
            echo $child->name;
        }
    }
}

You may be able to rewrite the “if ( $children…” into a while loop if you need more recursion than that.