The setting Events hamburger menu calendar link doesn’t seem to do anything. A link to /calendar doesn’t show up in the hamburger menu nor in the sidebar if I enable that.
However, using Customize in the menu itself, I can add the link manually and it works regardless of the setting being enabled or not.
Thanks for the report. The customisations have been deprecated by Discourse itself, making these settings redundant. As you say you can now just add the links yourself. I’ve removed the settings from the plugin.
I’ve used this plugin for a few years, so I knew what to expect. But I guess new users wouldn’t know that there is such a thing as /calendar. Might be a good idea to tell them somehow.