If we try to resolve an issue that has completed tasks in any language other than English, we get an error that the issue cannot be closed when tasks are open.
We have tested this in Dutch and German, over multiple issues and it does not let you resolve. We left a time delay to see if it was because the tasks were not updating straight away but even after two days this did not work. However in English it works fine.
In Configure Application, open the Incident Business Object and click on the Business Rules thumbnail
Expand the Validation rules
Add or replace the Validation Rule on the Incident that checks for Active Tasks with the following:
$(Status:language != "Closed" && Status:language != "Resolved" ||
"$(Status:language == 'Completed' || Status:language == 'Cancelled' || Status:language == 'Rejected')"))