Centova Cast has no way of knowing you added any tracks if you added them straight to the user's media directory, so no, it won't pick them up automatically. You need to update the library manually in that case, using the standard command:
/usr/local/centovacast/bin/ccmanage reindex username
Also remember that it's a bad idea to scp/sftp files directly as root, unless you change the ownerships to 'ccuser' after doing so. Otherwise the user will receive errors if they try to move/rename files in the file manager later.