Features used to implement the example

• Set a field as a function of other fields

Example: Set the value of a field of type "User Picker" depending on other field's value

I am looking to be able to assign an issue to a reporter or a user depending on the project name. I am using Jira Workflow Toolbox and it works great if I know the user to assign to. But how can I specify assigning to a role?

For example:

(ProjectA)user1
(ProjectB)user2
(ProjectC)reporter <-- This should assign back to the reporter if the project name is Project C

I didn't understood your question at first instance. Actually, the plugin supports nicely what you are trying to do. You only have to introduce the ID of virtual field Reporter, i.e. %{00006}

Use the following setting rules:

(ProjectA)user1
(ProjectB)user2
(ProjectC)%{00006}

Nevertheless, next version of the plugin will have support to set field of type User (including Assignee, Reporter, etc) or Multi-User with a Project Role. This was what I understood from your question at first instance.