Usually only rail replacement buses are included.

A bus in Cornwall won't be included, do not count on that. Fortunately the British government subsidises 2£ bus tickets this year (much less than usual !).

Which route are you looking at ?

Thank you for the information!

I thought about visiting the Western coast: First step is St. Michael’s Mount and the last one St. Ives. 
To my surprise, the buses are not running late as they do in London for instance. Most of them will not take you anywhere after 6pm which is a bit sad because I won’t be able to see as much of Cornwall as I would like to.

Well services in the countryside aren't as frequent or do not run as late as in bigger cities. That's the case everywhere, incl. the UK and Germany. Fortunately the connections are still better than in France for example… the last bus between Marazion/St. Michael's Mount and Penzance is at 23:00.

St. Michael's Mount is about an hour walk along the coast and the railway from Penzance train station (there are buses too). St. Ives has a train station :)

There are multiple small railways diverging from the Cornish mainline : to St. Ives, Newquay, Falmouth, Looe,… Honestly the British railway system is very good (despite the extremely expensive prices).

Enjoy your trip ! Do not hesitate for questions, I went to Cornwall in October 2021.

Unfortunately, I already know about the lack of public transportation in Germany because I was born and raised there. 
Nevertheless, I am persuaded that I will figure out some routes in Cornwall, thanks for the inspiration!

I will only stay for 4 days. After that I am on my way to Edinburgh. 

I will let you know if I need help. Thanks!

Anna

Full bus timetables and map for Cornwall https://www.transportforcornwall.co.uk/wp-content/uploads/TFC-MAY-2023-Guide-May-28th-WEB-1.pdf

as above fares in England are currently a flat £2 or in Cornwall there is a day ticket for all routes listed above for £7

https://www.transportforcornwall.co.uk/

London is an exception in having a comprehensive network of 24 Hour buses.

Outside of London bus services in Britain are almost exclusively run by private companies on a commercial basis and the service levels in many places is very poor. Cornwall would be considered one of the better served regions.

Ahhhh okay, thanks again! Those information are very helpful!

If the Eurail planner app comes up with a bus does that mean it is covered by the pass eg Taranto to Potenza in Italy 

Probably yes in this case. Date and departure time would help. I had a look at tomorrow and it looks there are rail replacement buses. Some of them replace intercity trains and require a reservation (should be €3); others replace regional trains and don't have reservations.

In Italy rail replacement busses have this numbers:

Local trains (regionale), 2 letters of the trenitalia regional office that normaly runs the train. In your case PZ for Potenza and 3 numbers for the bus number.

Long distance trains have a L for Long Distance and 3 numbers and sometimes a letter at the end.

for EC rail replacements a EC and a number.

Thanks for your help