I think what the 27 routes refers to is the no of routes or destinations that GWR▸ are obliged to put into their timetables as a bus connection from a railhead like Bodmin Parkway to Wadebridge and Padstow, The Lizard and Bude are other places. Minehead from Taunton is another 'bus link' that springs to mind.
There are some details in some timetables. Timetable K1 gives times to Wadebridge/Padstow, Eden Project and Helston. Nothing for the Lizard. D1 gives times for Bude and Exeter Airport. I can see no timetable that provides bus information for Minehead.
There is mention of bus services from Moreton in Marsh in the T6 timetable, but no times, just links to the operators.
Nowhere near details of 27 services across the GWR network. As for an obligation to provide the information, I can find no such requirement in the franchise agreement.