If it can start from LTT by 1800 and reach SBC by 1600 and to CBE by 2300, it would be better. Return can be at 0600 CBE, 1300 at SBC and 1100 at LTT. In the current TT from Mumbai, one is not sure when you will reach your destination. In the return, you are wasting 2 days.
For a CBE person, a train from CBE to Mumbai via Shoranur, Konkan is very much advantageous. But no train runs in this route (except for a weekly). If a new train with RSA can be planned, it will be beneficial.