In its main file tree, Cervisia does not display all files which are actually there. This is analogue to cvs itself and helps to avoid clutter caused by uninteresting stuff like object files. Cervisia tries to mimic cvs's behaviour as close as possible, i.e. it gets ignore lists from the following sources:
A static list of entries which includes things like *.o and core. For details, see the CVS documentation.
The file $HOME/.cvsignore.
The environment variable $CVSIGNORE
The .cvsignore file in the respective directory
cvs itself additionally looks up entries in $CVSROOT/CVSROOT/cvsignore, but this is a file on the server, and Cervisia should be able to start up offline. If you are working with a group that prefers to use an ignore list on the server, it's probably a good idea to take a look which patterns are listed there and to put them into the .cvsignore file in your home directory.