Currently no data about Familiars is published to Census. As Familiars are a potential revenue source, making more information available about which familiars players have and haven't collected and how to get more seems like a potential win-win.
Well.. some data about familiars is published as I can get a list of my current familiars and my currently equipped one. Granted, doesn't appear to be any data concerning their stats though.. unless I'm missing it.
There is a familiars tab on the character sheet that shows which ones you have and also the stats. If you are using a custom UI, then maybe you don't see the tab, but the original UI has one.
It would be really helpful to be able to look up your various alts to see what familiars each has so you can note who needs to improve things. Yes, I can log into each character sequentially, but slower.