One generic way of knowing what template is called is to turn your eZ Publish into development mode. Here are the few settings you should modify in site.ini.append.php, before clearing all caches and reloading the page showing Feedback form object :
I've copied the class "feedbak form" from the administration section so as to both modify it my way and keep the original untouched. It requires the node's template as it is a new class.
I'd like to know how I can create a new template for the copy of the "feedback form" class.
As a small educative starter, i'd recommend reading this short description of the template override system : http://doc.ez.no/eZ-Publish/Technical-manual/4.x/Templates/The-template-override-system
Concerning your specific problem, you will need to open your front-end siteaccess' override.ini.append.php file, spot the override rule related to the feedback_form content class, copy the whole block and alter the 'Match' condition by replacing the original content class identifier by the new one. The new content class identifier can be found in the back-office, where you duplicated the feedback form class : Setup > Classes.
Let us know how things go, Cheers,
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Nicolas Pastorino
Director Community - eZ
Member of the Community Project Board