Thanks for the long response. Yes the two who died at or on the way to hospital (info isn't quite clear) were the initial survivors aboard the bus. Two people were thrown from it and survived, 12 in total died (10 immediately, 2 soon after). I saw that the reddit-headline lists 10, maybe I wrote it too confusingly with initial dead vs later/total dead.

As far as I know the bus driver (who died) wasn't thrown from the vehicle, some sources on the accident indicate that he died "where he sat".

The common assumption is (simplified) that a more "capable" guard might not have forgotten the cap, or the second train. And yes the cap you have to place yourself is really weak safety, it's a good thing that they introduced the signal-system connection afterwards.

By the way, reducing level crossings is an ongoing issue in German rail-infrastructure, with focus on rural barrier-less ones. An often cited reason not to upgrade them (or replace them with underpasses) is, you probably guessed it, cost. There's a line near me where they planned to remove some crossings via new overpasses (for higher train speeds), built all of one overpass and then decided not to, after all. Now (years later), a second overpass may be built.

P.S.: I saw your comment on reddit, I do check there, but I have to respond here. Thanks for commenting here too!