BOSA Accessibility Check is a client-side JavaScript application that checks a HTML document or source code, and detects violations of a defined coding standard. Comes with standards that cover the three conformance levels of the W3C's Web Content Accessibility Guidelines (WCAG) 2.1 and the U.S. Section 508 legislation.
On https://www.digitalwallonia.be/fr it won't show itself, with javascript errors in the browser console log
On https://www.wallonie.be/fr it will run, but you can't access the report page, with errors in the browser console log.
Both work correctly on HTML Codesniffer release 2.1.1 (though that one is "old", released in 2017)