I had a very complex dashboard with around 40 to 45 sheets in it. After i created the dashboard, i published the data source to the server with all the calculated fields in it. Once i switched the dashboard to the published connection, i had to edit some of the calculations i entered in the calculated fields. Ofcourse i lost the right to edit the fields in the published connection as it is part of the published connection now. Work around is to create a copy of the object. This is re-work because of the fact that we are duplicating the calculated field and the time and effort it takes to replace the original field in all the sheets with the duplicated field and re-apply all the formatting changes. I would recommend to provide this capability to edit the calculated fields even if it is part of the published data source connection.
PS: Tableau's note on this problem is mentioned in the provided link