We'll never know. But I suppose that the Germans had no other way to represent the ʂ of barszcz in their barbaric language...
As surprising as it sounds, even barbarians have standards.

I am surprised that nobody else is commenting on the page. I am actually looking forward to today's update! (Unless it boils down to 'trolls all dead, the group leaves the hotel and goes back to fighting the bear' -- I so want to see them fight something other than a bear. Or Surma. Maybe Sigrun could be awesome again?)
I suppose that there's a broad consensus that the BOOOM and smoke mirror changing conditions in the mages' real world surroundings, i.e.,
within the walk-in freezer. Which would indicate that a) some sort of powerful firearm/explosive/incendiary was discharged but b) did
not have much effect
inside the freezer (else -> crispy mages), which, in turn, leaves the trollpile immediately outside as the likeliest target, and thus the other team members as the ones who discharged it.
Trolldom could certainly cause a BOOOM and maybe a bit of some sort of smoke, but unless the hotel had a powder room, I don't see how they could cause
both at once.