Hi Constantine,
Greetings from Syncfusion.
Query: Grid localization - It seems that localization is not fully working in the boolean column.
We have validated your query and would like to inform you that by default the Excel filter values are displayed in filter dialog based on the provided DataSource in the Grid. If you want to change the values in filter dialog based on your locale, then you can achieve your requirement by using FilterItemTemplate.
Please let us know if you have any concerns.
Regards,
Rahul