But what problems? It was everything according to Lelouch's keikaku. If Kallen got some problem with someone, that person is Lelouch, not Suzaku. Kallen even said that she understood Suzaku's position till the final fight. I think they're pretty even and fine with themselves at the end of the series and both loved Lelouch very deeply and knows that. There's no resentment between them.
No need for Nunna to try and be the peacemaker when everything is already peaceful. Now let's grab a kalulu beer, blade.