While I have no reasonable explanation for why they ordered FOUR Australian N3DS devices.
I think the testing and verification is merely a matter of being thorough.
Is there that big of a difference between EUR and JAP devices/ROM's? Not necessarily.
However, as you say, it sounds like they've already used a Japanese N3DS to test their thing, since they previously mentioned N3DS support.
Now, considering the "A great platform to test EUR ROMs" - it raises the question, did the JAP device not support EUR/US ROMs?
Or are they really just being thorough?
It could either one of those. I hope it's the latter. Although it's kinda.. Well.. Ok. Just being really torough I guess. Might as well deliver a product based on facts rather than "Eeeh we GUESS it works on EUR N3DS since well.. It worked on JAP N3DS".
As for what I wanted to mention earlier. There's a reason why Gateway themselves haven't forwarded such information.
The situation is already chaotic, but adding that little line of info would even make it more troublesome. I mean, things like this would pop up: "Hey! You said you support N3DS! So why are you ordering FOUR aussie N3DS NOW after announcing it'd work?"
It'd be something along those lines. With this added extra measure, they'll be sure to deliver the best patch in a proper fashion.
As for why four.. Well.. I'll speculate that they want to test various devices incase they receive a defective one or something. Y'never know.
Right now, we can only hope we'll receive the teaser video by next weekend.