Hieee...
So I also agree with you that being a Mastermind doesn't means he should know everything but it means know how to play your own game.
Regarding this track I think that his revenge includes Riddhima,I know many people will not agree but unfortunately he thinks Riddhima as gold digger and betrayer...I am saying this becoz regarding Riddhima he himself always said that he can't understand her,like a puzzle according to him infact its the reason he married her but then he gave his heart a chance without any complete clarity regarding her but just before fall if we look at the scenes then he broke down before her told her how important Ragini is but Riddhima even after knowing all this not disclosed about Ragini,I know she has reasons but point is Vansh don't know those reasons then that watch which Riddhima took found at murder spot,we know how it reached there but Vansh doesn't know and then Kabir's exposing her truth of being spy(he always knew she is a spy but then he thought she let go of that but now all these things raised suspicion again in his mind regarding her being spy)we shouldn't forget that all sia recording,clip of taking Riddhima away were there as a proof,and with all these suspicions he fell from that cliff and Returned as Vihaan to know about Riddhima reasons then again what he came to know that she hates kabir which somewhere proves her connections with Kabir...so she was agreed to marry him then bought him as Vansh to stop marriage and then her desperation regarding property,she even ready to go to jail agreed for his demands,we know her reasons but vansh doesn't and also if he is stranger she can't tell reasons,she can even say to him that Kabir is a threat to family and she want to throw him out or bring out his truth if not more but she has her reasons,her thought process.
Now regarding Kabir,I have a feeling that his revenge includes Kabir but intensity could not be more because he always knew Kabir was after him so kabir is like a regular enemy.
About AP I guess we have to wait,I just want that he knows or have an idea regarding her but we have to wait whether he has or Sia is the only hope.
Lastly I can't see Riddhima suffering more but now I think she is going to.Feeling bad for that girl,she is so selfless and alone,she doesn't even have anybody to share her pain,its really disheartening to see her cry before Vansh's photo all alone and now the same Vansh God knows what is going to do.
So its all my thoughts and I always says I don't trust cvs so they can do anything path breaking also,let's see.