Hi,

To raise forbidden and not found error,You can refer the given code below:
from werkzeug.exceptions import Forbidden, NotFound

@route(['/route'], type='http',
           auth='user',
           website=True)def function(self):
     if not request.env.user.has_group( 'module_name.group_id'):         

​return Forbidden()     

     else:         

         return NotFound()

Hope it helps