Do you mean, can each WordPress post-type be set so that it publishes to a specific category on Discourse?
You can now choose the category to publish to when you create a post. But all the available categories are displayed for each post-type. If you want to control what categories can be used for a post-type, I think the plugin could a filter the Discourse categories that are displayed in the ‘publish to Discourse’ meta box. That filter could be used in a theme to only allow publishing to specific categories for each post-type.
This would only require a small change in the plugin’s code, but would require some custom code in the WordPress theme.