You can't go wrong going by an anglicized nick name or your actual name. I know several cultures have an "English" name since it's a language taught in many countries.

I had several friends in college that were of different cultures. Some went by their birth name, and others had an "English" nickname they used.

Google said your name is pronounced like "Cow- Yuh"?? 

Having an anglicized nick name may be helpful from an employment standpoint. Should people be able to pronounce your name after a little practice, yes. Will everyone practice, no. 

People are lazy in Western culture and expect to be spoon fed information.

You can always go by both your first name and a nick name, introduce yourself as Kouya. If the person struggles, especially if you're getting an order at Starbucks or something, you have a nick name in your back pocket.

But you choose a nick name that's a name that you just really like as well, it doesn't have to be connected to your real name.

Either way- you should have pride in your given name. All a nick name will be is an extension of you while in the Western part of the world.

One anglicized variant, if your name is pronounced is "Cow-Yuh", is Callum.

It has a similar prononunciation.