Yes, you can change the language to: English, Spanish, Portuguese and Chinese.

To set up the language, access to the "File" option and then, "Preferences". 

You can also click on the "Settings" icon.

A pop-up window will open. Choose the language you would like to work with to set up the language and click on ok. 

Finally, you will see a message informing you that the software will close to save the changes. You will have to open again RiftGG to see the language you just set-up.