CrossOver will automatically display its user interface in the same language as the operating system, but you can also set CrossOver to use a different language by specifying the environment variables:
LC_ALL, LANG and LANGUAGE
For example, you can set CrossOver to a Simplified Chinese GUI by modifying the Exec line in the files:
$HOME/.local/share/applications/cxmenu-cxoffice-0-29ra4ke-CrossOver.desktop (if the .bin shell installer was used)
Exec=env LC_ALL=zh_CN.UTF-8 LANG=zh_CN.UTF-8 LANGUAGE=zh_CN.UTF-8 /opt/cxoffice/bin/crossover %u
zh_CN.UTF-8 should also then be uncommented in the file
After these edits you'll need to run
sudo locale-gen for the changes to take effect and relaunch CrossOver.