I work extensively in Brazil with the forest industry and universities. Brazilian Koa is neither Koa or Acacia. The botanical name is Astronium fraxinifolium (sometimes Astronium graveolens), commonly called"Gonçolo alves" or sometimes Tigerwood in Brazil. It was initially marketed as Tigerwood. When marketed as "Brazilian Koa" it sells better and for a higher price, because of Koa's reputation. This is kind of like calling Patagonian toothfish "Chilean Sea Bass" and shark meat cut into round pieces "Scallops".
However, this wood is generally a great product, very hard and rot resistant. However, it does vary in quality, hardness and price. It has "arrived" as a product, so it is not quite the bargain that it used to be when marketed initially as Tigerwood. Key is to get a look at the product before buying if you can.