Same problem here. I used:
add_filter( ‘woocommerce_product_single_add_to_cart_text’, ‘woo_custom_cart_button_text’ );
function woo_custom_cart_button_text() {
return __( ‘My Button Text’, ‘woocommerce’ );
}
After updating to 2.1.1 it displays standard text “add to cart” only. Woocommerce Poor guys swiss knife plugin cannot change the text either.
On https://cursus.5ct.info/?post_type=product you may see what I mean; the Dutch version of “add to cart” is very long.