I say this to justify a theory. Hence I focus on the theory and not to discredit another theory as a strawman. But I noted that I would if called on, so here go

I say this to justify a theory. Hence I focus on the theory and not to discredit another theory as a strawman. But I noted that I would if called on, so here goes: * We know that anciently transmitted etymologies are unreliable. They were prone to folk etymology as much as we are, if not more so. * I guess the most prolific onomatopoeia are simply way way older than this word. And they proliferate because a cuckoo really doesn't make any other sound than that. Whereas language is a lot more diverse. It might have frequent recognizable features, even ones sounding like "bar", I don't even doubt that. After all we have them too, argh. I can imagine that it is a word pronounced in allusion to the foreign language, even a foreign word. * I also hear the theory that some sound imitations pop up all over the place, independently. At least that is obviously highly unlikely to have happened here. * There is very little chance to actually experience a foreigner, which would be needed to reinforce the perception as sound imitation. So it's more likely this was told as a joke for reference. That invites the thought that the joke was just that and outweighed the etymon. Most people don't really care about etymology anyway. * Ideophone fits the idea much better. * It's childish; foreign policy is not.