Formulas

If so and assuming that in your Roles table that a Supervisor is Record ID# 1

Create a Formula Text Field in the Tasks Table:

If ( [Related Role]=1, [Role Name], "No Supervisor" )

You set the the message in the If Statement to what ever is relevant to your business process.

If you have a different architecture, then you need to use the Look Up fields to get the relevant information to the Tasks Table so you can display it when there is Supervisor assigned the Task.