I have fixed it by adding
<script>
(function($){
$("#adminForm").validationEngine('attach',{prettySelect:true,useSuffix:"_chzn"});
})(jQuery)
</script>
in the form for the item (in my case component/fork/view/record/tpml/createrecord_form.php)
But I will take it one step further and fork the headerDeclaration, so I can utilize this on every form.
I did not test it with a relation field, but will soon
Validation also does not work on textarea with rich text editor (ajax validation that is, validation itself works)