Okay I'm back and I will answer this to the best of my understanding...
Was Runjhun right in acting and saying what she said to Guddu in Kalsanwali's room? Would you be as forgiving as her? What would you have done if you were in Runjhun's place?
Runjhun says to Guddu that what Vishnu and Kalsanwali did, didn't hurt her, but what Guddu did hurt her. In my opinion she was right in acting the way she did. She's not trying to be mahaan or anything. I think the saying "teaching the man to fish is better than giving him a fish" is sort of apt here. I think she wants Guddu to be able to come on his own that there are consequences to his actions that every one can be held accountable for their actions. If he exacts revenge it's good and done. Then what. Revenge is a vicious cycle, as much as some people might consider it satisfying. I mean it started a whole chain of events between them back and forth. She wants Guddu to not respond to his impulses but rather take the time to think before he acts. Her feelings for the man aside she is trying to make him a good man. He can't be that if he acts as he wishes and thinks that revenge is the best measure and answer to everything. Sometimes fire with fire isn't the answer.
Also he never apologized to her for what he did, nor did he admit to her that he was wrong, even though he made the tonic for her. He knew what Kalsanwali had done, but even as he was giving her the tonic he didn't say I got it wrong. What's the point of putting medicine on the wound if you're going to hurt the person again the next time.
Was Guddu right in exacting revenege from Kalsanwali for messing up the food? Was his anger justified? What would you have done if you were in Guddu's place?
His anger is justified. She tampered with his food after all. I probably would have mixed spices in her food too...tricked her into eating some spicy food. LOL Just kidding. But like Runjhun said he was angry at Kalsanwali, that's fine. But if he'd held himself accountable for his own wrong doings, then maybe he could have gone around judging other people. The Kabir doha "Bura Jo Dekhan Main Chala, Bura Naa Milya Koye Jo Munn Khoja Apnaa, To Mujhse Bura Naa Koye" is apt here...or the other saying people with glass houses can't throw stones at other people's houses. He was justified but that didn't make it completely right for him to do, because he was wrong too. Runjhun is unaffected by Kalsanwali and Vishnu's actions, to her what Guddu does matter most. She has no problem when strength is used at the right time for the right reasons, like she told to the people who came for the proposal. She told Guddu that she will stand by his side (be it duty bound or for any other reason) and she expects the same out of him, and not be swayed in by emotions of anger and revenge that would cloud his judgement. He has to trust her, which he doesn't seem to yet. Trust is part logic and part emotion, in some ways.
Does Kalsanwali deserve punishment? Are we justified in judging or punishing others?
Kalsanwali deserves punishment, but I don't think we're ever justified in judging others, even though sometimes we do it subconsciously, and are most all guilty of it. Punishing depends on the situation. It can be justified again that doesn't necessarily make it the right thing to do. Besides justified or not, I've found that sometimes people tend to punish themselves all on their own without having to do anything, they manage to self sabotage themselves without you having to waste any effort.
That's all from my brain...