I have installed Roundcube 0.4 on my server and the romanian language interface.
When attempting to create a new account, only the inbox folder is displayed. Deleting or sending a message from the inbox to the junk folder these folders don't show up immediately, but rather after several deleted/flagged messages.
When trying to configure the folder list from the options menu, I can not check those folders to be shown, but creating a subfolder in one of them usually does the trick.
What imap server are you using?
What is $rcmail_config['create_default_folders'] and $rcmail_config['default_imap_folders'] set to in your RC config?
Generally, the creation of default of folders is the job of the imap server, not the imap client.