Edit Kendo-Template
You can read how Kendo templates work here. You can assign the templates to a user in the user settings under Resource Planning within the "Bar label" section.
You can specify the template for the bar caption in the Kendo-Template section and the templates for the tooltip of the assignment bar in the Kendo-Template for tooltip section.
In the templates, you can use the variable "event" to enter the data for the assignment. You can access additional data fields as follows: event.CustFields['kuind.test'] or event.CustFields['kuind.test'].
Only the additional data that are also in IND fields for planning board can be accessed. Fields for an assignment can be taken from DevTools (switch to network for this, find the calls ResourcePlanningScheduler/GetData).
You can also use the variables "settings", which contain the setting of the Planning board. The settings can also be taken from the DevTools (switch to network, find the calls ResourcePlanningScheduler/GetInitialSettings).