Sorry about the issue. I'm split between both the Raku and Perl tracks, and don't currently have much time for keeping up on maintenance for either unfortunately.
Please post issues on the Exercism forum if you encounter anything else. I only learned of this issue because someone else spotted this post and reported it there.
I signed up and took a look, and you are indeed correct. _Excorcism's_ lesson plan is broken. Raku is not. I have no idea why they are doing things the way they are, but what they have is not setup correctly. It's a shame. That might have been a decent teaching environment.
I have found better luck using repl.it to test code, and working through the Raku Course at https://course.raku.org/
I've tried the websites, I've tried the CLI, etc. It just won't let me try. I've never had the issue with any other language tracks