The OX app does indeed replace the UCS spam filter mechanism.
OX does indeed create the default folders by default with German names (it is a German company). But both the administrator and users can change the folders names:
The defaults are set in /opt/open-xchange/etc/AdminUser.properties. Please use UCR for settings in .property files. For example usage look at
ucr search ^ox/cfg/AdminUser.properties/
OX configuration options are explained here: https://documentation.open-xchange.com/components/middleware/config/7.10.2/
Users can set the folders they want to use for sent/trash/etc in settings→accounts.