Unless you're hung up on having to have Acacia grown from a tree in Hawaii (Koa), Acacia ukuleles can be very beautiful and sound very much like Koa. I doubt an acacia and a koa built exactly the same way would sound any more different than two koas built exactly the same way would. No two ukuleles sound exactly alike, and once you get it home it will be your amazing ukulele. But if you're hung up on being able to call your ukulele koa, then acacia's not going to cut it for you. Take the shirt test: do you need to have a certain designer label inside your shirt or are you more concerned with the quality of the shirt?
"Acacia" on its own doesn't tell you much. Acacias vary from scrubby shrubs with no usable wood, to Acacia peuce described in the Wood Database as one of the heaviest and hardest woods on earth!
I've built with both Acacia koa (from Hawaii) and with Acacia melanoxylon (Tasmanian or Australian Blackwood). Their appearance is similar, though the blackwood is darker, but they aren't the same to build with - the Blackwood was denser and stiffer, and needed to be very thin to work as a uke. Both sounded good, but different. That's only one data point, but it does come from someone who has used both species. And I've played Blackwood ukes not made by me which don't, to my ears, sound the same as koa, so that's another few data points.
I've no idea which species is used by the Taiwanese makers, though a web search suggests Acacia confusa. I've no experience working with that.
It's worth bearing in mind that Acacia koa is rare, because it only comes from Hawaii, and thus expensive. The other koas are invasive species which grow like weeds, and so should be no or very little more expensive than any other useful ukulele wood.
The other thing to consider is that, so far as I can discover, only Hawaiian Acacia koa will produce the very spectacular figuring you see on some ukes. All the other acacias seem to be much plainer.
I suspect an Acaia confusa uke, or an Acacia melanoxylon one, could sound pretty good though not quite the same. There's nothing magic in Acacia koa itself, just the tradition and its rarity. But don't expect a non-koa acacia to look as spectacular as some koa ukes do (that said, I own a Kumalae soprano from the 1920s which is made of koa, and is about as plain as could be in appearance).