Well, this IS a remarkable find.

I refer the reader to Figure 41

and its discussion

Apparently metal artefacts were ovverrun by the impact blast cloud!

"At another site, finds from the Celtic culture together with the peculiar impact material exhibit strange surfaces pointing to sudden heating on one side only (Fig. 41)"

"Taking into account the sample of thermally shocked coins from the late Latène period, we tend to set the Chiemgau impact event into that period"

This suggests that within recorded history at least one set of communities WAS destroyed by an impact event, with probable loss of life.

The authors get a bit fanciful in ascribing a significant fraction of energy to atmospheric combustion of a Methane-ice comet. The kinetic energy of the impactor is at least one or two orders of magnitude higher than the chemical energy of combustion of the same mass. Nonetheless, a ~1km impactor is not a trivial event - many tens of megatons are involved.

[All the above still doesn't make EP "right",IMHO, but it does start to move the scientific discussion forward,]