Do you mean this one:
https://github.com/omer-faruq/appstore.koplugin/ ?
I've tried it, it worked. But I deleted the plugin because I really only use 3 plugins and 1 patch on KoReader. If they won't work with an updated KoReader I just look them up, one plugin usually gets updated with each new KoReader version anyway (Project Title). Another plugin (Bookshelf) seems to get updates every other day. Most of the new features I don't need anyway, so I really don't need to update this one with each new version.
The third plugin is the Shortcutstoolbar, which I didn't need to update for the most recent stable KoReader version.