Hey Neil.
I'm not sure how your renderfarm is configured, but Ziva VFX should output some information to the Maya script editor when each substep in completed.
If this output is not captured by your render queuing software, the same information can be found in the Ziva log file, and is appended at each substep. (You may need to ask your IT department where to find the log - when you first load the plugin, it will inform you of its location in the Maya script editor - on this computer for instance, my log file is directed to this location:
// ziva 2018-11-23 08:57:57.053 NOTE| Logging to file "C:\Users\jamesj\AppData\Local\Temp\ziva-maya-log-9c18-036d-fbf6-e3c2.txt" //
I hope you find this information helpful.
-jj