There isn’t a lot of documentation on using JavaScript with ACF. There is this document https://www.advancedcustomfields.com/resources/adding-custom-javascript-fields/. Beyond this you’ll need to find examples of how other people have done this. I can remember several topics on this forum on the subject and you might be able to find those.
The field keys if that’s what you’re talking about that look something like this field_12345677 are randomly generated, but this is what you need to use when targeting the field using JavaScript.
I have some examples of using JS in a different way, by extending the acf object, but nothing that does what you’re looking for. But you can look at this to see how you can target the fields https://github.com/Hube2/acf-dynamic-ajax-select-example
