While the module does work for user 1 the module doesn't work for regular authenticated users, right now. It seems there is a permission required that doesn't exist.
Install Prismjs module
Enable button and filter in /admin/config/content/formats/manage/basic_html?destination=/admin/config/content/formats
save the form
enable the forum module as well
create a forum topic as user 1 or admin and add some examples in the body useing the prism js button
save the content
create a regular authenticated user
make sure that authenticated users have permission to write comments
log in as authenticated user not user 1
create a comment for your forum topic
click the prism button
result: The JS console shows {"message":"The \u0027use text format advanced\u0027 permission is required."} while the statuscode of /prism-js/dialog?_wrapper_format=drupal_modal is 403
So currently there is no chance usual users can use prism.
find root cause
create a patch
review patch
re-release
1.1
Code
Hi @Joachim Namyslo Thank you for the bug report. I've adjusted the permissions for the route, and it appears to be working now. Could you please verify?
Works perfectly now. Even for Authenticated users without the administrator role