I have found what is the problem. It isn’t enough to localize just the labels e.g. ('Label','text_domain'). But also the variable itself – my code should be like this:
add_meta_box($this->_meta_box['id'], ($this->_meta_box['title'],'text_domain'), array(&$this, $this->_meta_box['function_callback']), $page, $this->_meta_box['context'], $this->_meta_box['priority']);