http://sr7wtu3yb6cv5zz4gshbjnc5cfofv5ulj6jkxgzej4zhupcsriahp6id.onion
Also librex and searxng are not offered as services in a way that i can point icecat to a certain domain, rather you have to find the instances you trust (or even better host them). Once I've been reaching out to debian to ask them to put icecat in the debian repository but that did not get much traction.