A few users in earlier threads have noticed that Castable V2 has a bit more trouble adhering to the build platform than some of the other resins. You implemented pretty much exactly the fix we’ve been recommending until we get a better understanding of the adhesion issues some users are having 
The larger rafts seem to help the parts stick to the platform and the holes in the center are a neat idea to help combat against warping. Your prints are looking great!