This sounds as if only the rich text editor HTML has been copied
without any JS behavior whatsoever. This happens when the empty form
(formset.empty_form) is initialized with a rich text widget. TinyMCE
and CKEditor (and other probably too) don't like it when they are
copied around, that's the reason for the richify/poorify methods to
exist in the first place.
I'd try coping either init_tinymce.html or init_ckeditor.html (in
feincms/templates/admin/content/richtext/) and starting from there.
Additionally, you'll have to set custom values for
FEINCMS_RICHTEXT_INIT_TEMPLATE and FEINCMS_RICHTEXT_INIT_CONTEXT. The
template would be 'admin/content/richtext/init_cleditor.html', the
context a dict of whatever context variables you need inside
init_cleditor.html (if any).
http://www.feinheit.ch/media/labs/feincms/contenttypes.html#module-feincms.content.richtext.models
Hope it helps,
Matthias