Well this level of confusion is highly disappointing.
There is a genus of trees called acacia. There are many different subspecies of of acacia, all over the world. Only one of those is "koa." (All koa is acacia, but not all acacia is koa.)
To be quite specific, there is a tree that *is* "acacia koa" that we commonly call "koa." It is native to Hawaii and is that tree that people think of when they hear "koa." Where there could be some genuine confusion, however, is that it is possible to grow the tree "acacia koa" in other places. There are acacia koa trees growing in California (or so my browsing of the internet tells me. I haven't seen them in person.) Does that make them "not really koa" because that specific tree wasn't grown in Hawaii?
I don't think that this is the confusion that is going on here, by the way. Twisted Wood has some instruments that they actually build in house in Canada (their "Pro" series) and some that are built in the far east for them. I would speculate that the far east built ones are made with some other kind of acacia (which is also likely grown in the far east) and simply called "koa." That kind of thing really irritates me.
(Note: I do suspect that growing conditions do change the wood and that acacia koa grown in the conditions in Hawaii will be somewhat different than acacia koa grown in, say, California.)