I'm learning Japanese and this is quite an interesting thing to hear. I am surprised by the number of things that do not quite have a simple analogue in English. It's a nice and compact phrase, though of course the danger with many of these is that they may be uncommon so risky to use, especially as a learner.

I'm actually not a native speaker either (I'm Finnish).

I think 八つ当たり might derive from the same idea as 八方 which means "every direction" even though it's literally "eight directions". I'm guessing the idea is that you're hitting things all over the place, even if it's not a suitable target.

EDIT: oh, I forgot to add that 八つ当たり is very common, so you definitely should look out for it to get an idea of how and when to use it.