What is the best way to reassign a role-assigned task to a specific user?

We've generally provided this type of functionality outside of Maestro core with some simple custom code dependant on the use case for the customer's workflow and management scenario.

Assignments are stored in the maestro_production_assignments entity table.
If you compare that table against the Reassignment form (maestro/src/Form/MaestroReassign.php) you'll see how we're doing the reassignment by maintaining the assign_type. The assign type will either be user or role.

You can augment the assignment record however you see fit outside of the constraints of Maestro's core.
You could conceivably form-alter the reassignment form to unhide the assign_type and make that a select box and thereby show/hide the appropriate "select_assigned_xxxx" form element. Then add your own submit handler to save the whole entity as in our save routine, we do not overwrite the assign_type.

It's a start for you. Let me know if this helps.

Thanks for your help _randy, I'll have a look at the code you are referencing and see what I can do.

I guess we'll have to add that feature to the task console somehow.

Many people fork the stock Maestro task console and customize it and maintain it themselves. Or use a views-based task console sole with your own custom view operations pseudo field for these types of operations.