Secondly, the contribution of its unit linked with the Internet market in Japan, as well as in some countries throughout South America, has been highlighted.
-It's a little hard to tell without the rest of the paragraph; you could say either one but it would change the meaning just slightly, and I'm afraid I can't explain it better than that. From that sentence, though, I would use "has been."
I also changed the "other countries" part because it sounded like Japan was located in South America. O_o
- For Teachers