The aggregates field is currently available only for kendoTreeListFooterTemplate:

https://www.telerik.com/kendo-angular-ui/components/treelist/aggregates/#toc-aggregating-flat-data

But in some scenarios, the aggregates need to be displayed inside the headers as well. Please provide the aggregates field in the kendoGridCellTemplate.

So far the only approach where this can be achieved is to use manual aggregation and some custom code:

   <ng-template kendoTreeListCellTemplate let-dataItem>
                    {{dataItem.name}} - <strong> {{ data.aggregates.name.count }} employee(s)</strong>
</ng-template>