Hi @ebud
As for your last question, can you please debug the code within the function. Can you confirm that the filter is fireing?
Perhaps there is a problem with the filter using the ‘name’. Instead, can you try using the field key?
There is no need to write a new field type.
As for AJAX JS stuff, this would take quite some time for me to explain, so I encourage you first to jump on google and research how to add JS to an admin screen (there is a ACF action called acf/input/admin_head) for this, and also learn how to perform an AJAX call.
Thanks
E
