In game data

[tempest]

Logs are obviously the simplest to parse. Just make sure you have the logging level set high enough. I don't know if you can or want to modify the server, but if you do, you could easily add additional output where you need it.
There's also the extended server info which e.g. CSL uses, but it can't tell you more than the server logs.
I could probably tell you something more helpful if I knew what data you want.