All you have to do is just by update your game (if you have already installed it) to the latest version and changing to English language in the Setting! Everything has been translated to English, including the cats’ names (unless you have customized them like I have).
The latest version update also added some new stuff, such as new Cowboy Western style items and a Western Style backyard that you can see in this screenshot.
There’s also new cats added in this version and some special cats have new interaction. (hint, there’s a train so…) I myself have only since one new special cat so far, and its favorite toy is the Cowboy Hat.
All in all it’s a super awesome update! I wonder what they are going to add for Christmas, or for New Year.