As long as your actually translating it, and not using a program, you'll be fine. But this takes time, and/or is expensive.
Keep in mind though, a lot of stuff in other countries is not as popular, so you still need to do keyword research to make sure you're not wasting your time.
A good example would be translating the American version of football into Spanish. No one cares about American football, except people in America.
No, it's not ethical though... if you rewrite it a bit, then you're in ethical territory. However, just the basic idea of you copying this and changing it a little to get by could be considered unethical. But who gives a sh!t? Go for it.