Here is a list of data types explained. They are all defined on the server so adding to that file won’t get you anything new.
client.loop() needs to be called as often as possible or you will get timeouts. It is a server set value. Maybe @rsiegel would know what the timeout length is? If you read through the DHT11/22 link I posted above you’ll see the troubles I was having with timeouts. Luckily I was using the standard Paho client so I was able to call mqttc.loop_start() which starts a new thread that runs independent of the main thread. My script was getting caught up trying to get a valid reading from the DHT sensor and hitting the timeout.