Since email alerts for updating a post isn’t really something that acf_form() does, I honestly don’t think that Johnathan will build it in. Basically it’s outside of the focus of the plugin.
Go back to @imaginedd’s answer and see acf/pre_save_post of acf/save_post here https://www.advancedcustomfields.com/resources/acfsave_post/ and use wp_mail() to send the notification https://developer.wordpress.org/reference/functions/wp_mail/.
