The web interface of every Tp-link repeater is configured with the different languages according to the region. The repeater will track the local region of your device and will automatically assign the language to you according to the region but it doesn't mean that a user cannot change the language. During the configuration process of the tplinkrepeater.net process, a user can choose the language through the drop-down list located on the top right corner of the main screen. You can change the language of the web interface of your repeater anytime according to your need.
http://setup-tplinkrepeater.net/