Hi Toby,
Thanks for reporting this!
We’re still deciding on what to do but we’ll probably add a note or warning to the relevant functions’ outputs. This warning will be temporary though, since the DataFrame is already ordered (“a DataFrame, ordered from best to worst model (measured by information criteria)”), and we also provide a rank number. So, a permanent warning would probably be redundant.
Regarding the synchronization of PyMC stats docs and ArviZ docs, this is a different but adjacent issue that will be dealt with too 
Hope this helps 