Is 13332 absolutely necessary? Because I am using 9918 and it seems to be working fine. I'll change it, but just wondering why.
13332 is not absolutely necessary, sentinel _should_ check terracoin.conf for rpcport= line.
Port 13333 is necessary for masternode p2p port.
Edit: If you must, you can also edit sentinel/lib/terracoin_config.py and change
default_port = 13332 if (network == 'mainnet') else 18332
to
default_port = 9918 if (network == 'mainnet') else 18332