Knowing Kalpi's nature and her complete worship of her mother, I seriously doubt that she would accept this compromise marriage. She certainly didn't look excited or even remotely happy when she saw Raghav approaching her with the sindoor.
Even if she was slightly inclined towards endorsing it, Kamala's hamla on herself will change her mind in a second. And, so it should. I would be highly disappointed with Kalpi if she quietly accepted this as a marriage and agreed to wait the year for him.
Besides, how can Rahgav quantify the period of revenge? How does he know if his mother will accept that the revenge is complete after a year? Is her anger valid only for a year?
I've seen the most asinine things happening in this show. But putting a time limit to seeking revenge has to take the cake in being the stupidest among them!