Hi @locomo
Thanks for the question. You can use a JS filter to hook in and run validation on any field! This is not yet documented but does work.
Use it like so:
* Note, this is jQuery
$(document).on('acf/validate_field', function( e, field ){
// vars
$field = $(field);
// set validation to false on this field
if( $field.find('input').val() == 'test' )
{
$field.data('validation', false);
}
});