Translate widget select

Hi everyone,
I’m experiencing an issue regarding the translation of chart_widget.js select options (Select Date Range and frequency selects from the dashboard view of a doctype). These are not marked as translatable strings in the original javascript file, so I cannot access them via Translation.
I can hardcode them but I would like to override them in order to include this customisation in my custom app. So far I’ve tried to copy chart_widget.js, made several modifications and tried to reach it via hooks (app_include_js). However, this didn’t work. Any idea on how to access this customised widget file?
Thanks in advance.