ignore the comment that I deleted, I was looking at the wrong hook.
You can get the field key of the field if that helps you.
acf.add_filter('wysiwyg_tinymce_settings', function( mceInit, id ){
// do something to mceInit
console.log(id);
console.log($('#'+id).closest('.acf-field').data('key'));
// return
return mceInit;
});