now that we've added hooks to various plugins we're finding the current method of obtaining the current module type is a bit fragile.

We need to add an extra param to plagiarism_get_form_elements_module() called $plugin which contains the $module->component (frankenstyle name) - so in mod forum it would look like this:
plagiarism_get_form_elements_module($mform, $ctx->get_course_context(), 'mod_forum');