The addTask action can be used to add arbitrary tasks to a job. However, you must know the parameter fields that each task uses and needs. Normally, the task provider doesn't document this. The following gives some examples. If the task you want is not one of the examples, the parameters can be discovered: see How to determine fields for addTask. If you get errors, you will need to debug the field problem by using the url used by the CLI tool in a browser so the errors are more prevalent. Run the action with --verbose and look for url that is being used and failing. This is the best that can be done until Bamboo provides proper REST APIs to help with this scenario.
See Task Type List to get more information about taskKey values available for your instance.