You should look into creating a new field type https://www.advancedcustomfields.com/resources/creating-a-new-field-type/, or someone that knows how to.
You could start by copying the functionality of the new radio field and instead of saving a value of 1 or 0 you could create field setting so that the on and off values can be defined when creating the field.
You might also try opening a support ticket https://support.advancedcustomfields.com/new-ticket/ which has a better chance of reaching the developer.
