DiscussionTools does not work in Walloon-language (wa) wikis. For example, https://wa.wiktionary.org/wiki/Wiccionaire:Nosse_cåbaret has no reply or subscribe buttons.

This is because date formatting in Walloon is implemented using custom code: https://gerrit.wikimedia.org/g/mediawiki/core/+/41e86d1198134e1758f9100cec520a8a9db3bce8/includes/languages/LanguageWa.php#42 instead of the usual date formatting patterns that DiscussionTools can use to parse the dates.

(I noticed this after @DLynch pointed out the custom date formatting code in his patch for T343343.)