I first noticed shortjournal was broken when I upgraded to 1.9.3. The bug is still there in 1.9.4, so I thought I would report it. Version 1.9.2 works just fine (so I downgraded to that one for the time being).
Not much to add. Thanks for the great software that I have been using for well over a decade!
This is not a bug. We don't (auto)complete arbitrary fields anymore, only fields that we know are relevant. For most fields, auto completion is more of a nuisance and a cost than being useful.
If you want to have more custom fields to be (auto) completed, you can add them using a hidden preference. See the Wiki for details.