Those all happened long before, some trains are running from Howrah since 1960s towards SER. That time SER didn't have proper facilities for originating/terminating hence HWH/ER was chosen. I remember 2-3 years back terminals of many trains were changed from Howrah to Shalimar including Coromandel, East Coast, Amravati, Jnaneswari etc
Vande Bharat was introduced from Howrah just to ensure high occupancy