This plugin is now being maintained by Richard (from Communiteq): Wp-discourse-shortcodes plugin - #91 by RGJ. It would be good to use the version of the plugin that is in their Github repo: https://github.com/communiteq/wp-discourse-shortcodes. I no longer have the plugin in my Github repo and I see there was an update made to the plugin on July 15th, 2021 in its new repo.
It’s been about a year since I last looked at the plugin’s code, so I’m not sure of the answers to your questions. Maybe someone who is currently using the plugin will be able to help you out.