I just tested the Shimeji and works well, is actually pretty well done even ^^ it's done used our jar version, just a bit oldy one that may not cover enough fixes.

Your main problem is the W11 though, that shitty system is still in development and even if lately got some useful updates for shimeji, is still an uncomplete system that will give trouble until it's more advanced.

The jar version of the Shimeji you are showing is from 2021, there are newer ones and if you update it you will have a more stable version for W11. People is using it successfully nowadays. If after updating doesn't work yet, I recommend to uninstall Java and reinstall it :3 maybe you got it corrupted somehow and is causing extra incompatibilities (the 8 you have should be the best, but you can try the newest version too if 8 gives trouble).

To update any shimeji you can use the tutorial at the bottom of this page:

http://cachomon.com/whatis.php (the "How to make older Shimeji work?" will show you how to update it)

If you will have more trouble in a future or wanna get more information about our Shimejis, feel free to join my Discord Server for that ^^ all the links in the Home page of my site http://cachomon.com/index.php