Under the i18n default messages, error messages (titleblacklist-forbidden-edit, titleblacklist-forbidden-move, titleblacklist-forbidden-upload, titleblacklist-forbidden-new-account) contain the actual regex tripped. This severely compromises the effectiveness of such rules, despite the regex rules being publicly viewable, especially given that even wikimedia wikis remove the following from the relevant MediaWiki page:

It matches the following blacklist entry: <code>$1</code>

I am requesting that this default be removed from the i18n messages.

Edit: doesn't seem to be any interest, especially when all the regex is already public at mediawiki:titleblacklist anyways