Hello ncls,
thanks for trying out WooCommerce Customizer sorry for the late reply — been a bit caught up in supporting our other WooCommerce plugins and releasing a rewrite for another this week.
I’d like to help you with the Customizer. Could you tell me what did you try doing and what didn’t work? I understood you wanted to customize the “Add to Cart Button Text”?
Do you have a screenshot of your settings? (From WP Admin: WooCommerce > Settings > then click on the ‘Customizer’ Tab).
If you tried filling up all fields with no avail, perhaps it’s also worth disabling other plugins except WooCommerce and the Customizer, and switch back to the default theme. Then re-enable one plugin one by one and compare if there are differences on the front-end. This is usually done to rule out a theme or plugin conflict that might be removing/filtering the button text you are trying to customize.
Cheers