Hi, and thank you for your interest!
yast-country is being translated using Weblate, a web tool designed to ease translating for both developers and translators.
Translation project for yast-country into English (United Kingdom) currently contains 183 strings for translation and is 86.3% complete.
If you would like to contribute to translation of yast-country, you need to register on this server.
Once you have activated your account just proceed to the translation section.