axander

Hello
Do you have any progress? I try the same.
With this code you successfully change the text of the buttons and the message:

function change_specific_availability_text( $availability ) {

    if ($availability[ 'class' ] == 'available-on-backorder') {

        $availability[ 'availability' ] = __( 'In the central warehouse', 'your-theme-textdomain' );

    }

    return $availability;

}

add_filter( 'woocommerce_get_availability', 'change_specific_availability_text', 20, 1 );

add_filter( 'woocommerce_loop_add_to_cart_link', 'zmena_textu_button_vypis_produktu', 10, 2 );
function zmena_textu_button_vypis_produktu( $text, $product ){
	if ( $product->is_on_backorder( 1 ) ) {
		$text = __( sprintf(
		'<a href="%s" data-quantity="%s" class="%s" %s>%s</a>',
		esc_url( $product->add_to_cart_url() ),
		esc_attr( isset( $args['quantity'] ) ? $args['quantity'] : 1 ),
		esc_attr( isset( $args['class'] ) ? $args['class'] : 'button' ),
		isset( $args['attributes'] ) ? wc_implode_html_attributes( $args['attributes'] ) : '',
		esc_html( ''Pre-Order' )
	), 'woocommerce' );
	}
	return $text;
}

add_filter( 'woocommerce_product_single_add_to_cart_text', 'wc_ninja_change_backorder_button', 10, 2 );
function wc_ninja_change_backorder_button( $text, $product ){
	if ( $product->is_on_backorder( 1 ) ) {
		$text = __( 'Pre-Order', 'woocommerce' );
	}
	return $text;
}