I fail to understand what really is the mystery here. If it is Tayaji and Kala being one and the same person, that is current known only to the mentally unstable dadu but they already showed how MJ has connected that Tayaji and Kala are working together as a team and they are trying to harm all four of them (MJ, Tara, Radha and Jairaj). I understand he is waiting for an opportune time to catch his tayaji red handed but then he needs to at least warn his father and his wife about how dangerous the man can be so that they can guard themselves. Now because of the ignorance of his brother's true face, Jairaj has engaged a lawyer recommended by his brother. That is going to hurt his case. So MJ and his secrets are not helping any one.
Yep I understand and agree with all of your points but it is a hindi serial after all. MJ has only connected that Tayaji is somewhat involved with the eunuch but he doesn't know that the eunuch's name is Kalavati yet (when he was being held captive by Kala, he asked who Kala was so he obviously doesn't know who Kalavati is). Since RP is so highly regarded by everyone, he needs solid evidence or elss no one believe him, not even Tara.
Idk I guess we have to be patient and watch the story unfold.