Sadly, most of the reviews saying that Shortkeys isn't working for them, are prime examples of people who haven't read (or don't understand) the extension's description as well as its documentation (on GitHub).
Some of them apparently don't understand how WebExtensions work.

If you're unsure something is working as intended and/or if you're trying to get help in that respect, you should use GitHub to file a ticket and not try to pressure them with these unwarranted reviews.

The devs haven't been noticeably active in the past couple of months, so I seriously hope that this extension will continue to work as long as possible.