Alright I think we can hope that she might come back to explain her actions to Sydney, but as for her being 'good,' I still doubt that is the case. She does care for Sydney, I think we have established that, but her obsession with Rambaldi is what drives her. Irina admitted, in A Dark Turn, to Jack that she was absolutely infatuated with Rambadli, I doubt she is whole heartidly good, though one could make the argument after her scene with Sloane, towards the start of the episode, when she told him never to speak of his paternal enstinct towards Sydney again, can be seen as motivation for her to have betrayed the CIA so she could go after Sloane herself, for Sydney's benefit, and imagine that she gets the rest of the Rambaldi artifacts as well.