krewDashboard, just like kintone, supports Japanese, English, and Chinese (Simplified and Traditional characters) languages.
If language settings of account has been changed in kintone environment as per the Changing the Display Language and Time Zone topic in kintone documentation, the user interface and messages of krewDashboard also get displayed in the language that has been set up.
Example: When language is set to Japanese
Example: When language is set to English