Coimbatore to Mangalore Shatabdi is unnecessary. Instead, Coimbatore to Madgaon/ Vasco overnight would be beneficial, with maintenance at CBE.
2 decades back, we had a proper train from Mangalore to Mumbai run with two train numbers Mumbai Madgaon Shatabdi and Madgaon Mangalore Shatabdi. Subsequently discontinued Why can't a Jan Shatabdi from MAQ to Mumbai benefitting entire Konkan railway areas?
If MAQ has slots available, it is better to take both YPR Mangalore triweekly express trains and Bijapur train to MAQ. CBE MAQ new train can start from MAJN.